The superpowers design specs and implementation plans live in
docs/superpowers/ as local planning artifacts and aren't meant to be
shipped as part of the gem or referenced from the user-facing
codebase. Add the directory to .gitignore and remove the existing
tracked files from the index. The files remain on disk for local
reference; they just won't be committed going forward.

Historical commits on main and earlier on this branch still contain
these files — this is a going-forward cleanup, not a history rewrite.

Move the information_schema.tables query and result transformation
out of the DatabaseAnalysis concern into a new
MysqlGenius::Core::Analysis::TableSizes class that takes a
Core::Connection. The concern's table_sizes action now builds an
ActiveRecordAdapter and delegates.

Behavior is byte-identical — same SQL, same result shape, same
per-table COUNT(*) fallback on error, same needs_optimize threshold.
The 5 new core specs use FakeAdapter to stub information_schema
results and verify row handling (hash access, MariaDB uppercase
column names, COUNT(*) error fallback, needs_optimize computation).

Code-review feedback on Task 1 of Phase 1b (commit 673c144):

1. RuboCop was regressing against the Phase 1a baseline. Fixed via
   `rubocop -A`:
   - RSpec/LeadingSubject: subject declared before let
   - RSpec/EmptyLineAfterFinalLet: blank line before subject
   - Style/WordArray: replaced %w[table_name ...] with string array
     literals (rubocop-shopify rejects %w containing underscores)

2. RSpec/ExampleLength: split the 31-line "hash per table" example
   into two smaller examples under the project's 25-line cap:
   - "returns one hash per BASE TABLE row" (top-level shape)
   - "includes full size metadata for each row" (numeric keys)

3. Added two coverage gap tests flagged by the reviewer:
   - nil size columns (e.g., MEMORY engine tables) coerce to 0.0
   - exact 10% boundary does not trigger needs_optimize

Move the left-prefix duplicate-index detection out of the
DatabaseAnalysis concern into a new
MysqlGenius::Core::Analysis::DuplicateIndexes class. The class takes
a Core::Connection plus a blocked_tables list and returns an array
of duplicate pairs, with the symmetrical-coverage dedup preserved.

The concern now builds an ActiveRecordAdapter and delegates,
passing blocked_tables from the configuration.

Move the performance_schema.events_statements_summary_by_digest
query out of the DatabaseAnalysis concern into a new
MysqlGenius::Core::Analysis::QueryStats class. Sort whitelist and
limit clamping now live in the class as VALID_SORTS and MAX_LIMIT
constants; the concern action parses params and hands them to
.call(sort:, limit:).

performance_schema availability errors continue to be caught by
the concern (Rails-specific ActiveRecord::StatementInvalid) and
rendered with the same user-facing message as before.

Move the performance_schema.table_io_waits_summary_by_index_usage
JOIN query out of the DatabaseAnalysis concern into a new
MysqlGenius::Core::Analysis::UnusedIndexes class. The class takes
a Core::Connection and returns an array of hashes with a
ready-to-run ALTER TABLE DROP INDEX statement per entry.

performance_schema availability errors stay in the concern's
ActiveRecord::StatementInvalid rescue.

Move SHOW GLOBAL STATUS / SHOW GLOBAL VARIABLES / SELECT VERSION()
collection and derived-metric computation out of the DatabaseAnalysis
concern into a new MysqlGenius::Core::Analysis::ServerOverview class.
Structure the output into server/connections/innodb/queries blocks
with the same keys and types as before.

This completes the 5-analysis extraction. DatabaseAnalysis concern
is now fully delegated to core; the concern's 5 actions have
shrunk from 295 lines of inline SQL and transformations to
47 lines of thin delegating wrappers.

Immutable frozen value object returned from Core::QueryRunner#run
(to be added in the next task). Contains columns, rows (post-masking),
row_count, execution_time_ms, and a truncated flag. Distinct from
Core::Result because it carries runtime metadata that plain results
don't need.

Holds the runner-specific subset of MysqlGenius::Configuration:
blocked_tables, masked_column_patterns, query_timeout_ms.
Frozen on initialize for defensive immutability.

Forward-declares the QueryRunner class so Config can be namespaced
under it. The full QueryRunner implementation lands in the next
task.

Core::QueryRunner owns SQL validation, row-limit application,
timeout-hint wrapping (MySQL vs MariaDB flavors), execution, column
masking, and timeout detection. Returns a Core::ExecutionResult
or raises Rejected / Timeout. Does NOT handle audit logging —
the concern still owns that.

The execute action in the QueryExecution concern now parses params,
builds an ActiveRecordAdapter and a QueryRunner::Config, calls
runner.run, and catches the specific error classes to produce the
same JSON response shapes as before. Rails-specific ActiveRecord
error translation stays in the concern.

Helpers validate_sql / apply_timeout_hint / mariadb? / apply_row_limit /
timeout_error? / masked_column? stay in the concern temporarily
because explain still uses validate_sql — they're removed in Task 9
when QueryExplainer replaces that last consumer.

13 new core specs cover happy-path execution, each rejection reason,
row limit application, column masking (single and multiple
patterns), truncation detection, MySQL vs MariaDB timeout hints,
timeout detection via error message, and non-timeout error
propagation.

Core::QueryExplainer wraps EXPLAIN around validated SELECT queries,
with an optional skip_validation flag for explaining captured slow
queries from mysql's own logs. Reuses Core::QueryRunner::Rejected
for validation failures and adds a new Core::QueryExplainer::Truncated
class for SQL that appears cut mid-statement.

The explain action in the QueryExecution concern now builds an
ActiveRecordAdapter + Config and delegates. The concern's private
helpers validate_sql, apply_timeout_hint, mariadb?, apply_row_limit,
timeout_error?, and masked_column? are deleted — they were the
internal plumbing that is now owned by Core::QueryRunner and
Core::QueryExplainer. sanitize_ai_sql and audit remain because
they're used elsewhere in the controller.

This completes Stage B and all code extraction for Phase 1b. The
next stage is the paired release to rubygems.

The workflow now builds and publishes mysql_genius-core first,
then mysql_genius, so the runtime dependency on mysql_genius-core
resolves at gem install time. The test job also runs the core
gem's spec suite to ensure it passes before publishing anything.

working-directory is used to keep the core gem's build artifacts
in gems/mysql_genius-core/ so the root-level "gem push
mysql_genius-*.gem" glob matches only the Rails adapter gem and
not the core gem.

- mysql_genius-core: 0.1.0.pre -> 0.4.0
- mysql_genius: 0.3.2 -> 0.4.0
- mysql_genius.gemspec dep: "~> 0.1.0.pre" -> "~> 0.4.0"
- CHANGELOG.md: ## Unreleased -> ## 0.4.0 with Phase 1b additions
- Added gems/mysql_genius-core/CHANGELOG.md documenting the first
  published release of the core gem

mysql_genius-core jumps straight from 0.1.0.pre to 0.4.0 so that
both gems release in lockstep under matching version numbers going
forward. The gemspec dep uses "~> 0.4.0" (allowing 0.4.x patches
but not 0.5) to enforce exact-minor pairing.

Also fixed the core gemspec:
- changelog_uri now points at gems/mysql_genius-core/CHANGELOG.md
  (was pointing at the adapter's CHANGELOG at the repo root)
- spec.files now includes CHANGELOG.md in the packaged gem

The next commit tags v0.4.0 and kicks off the publish workflow,
which will push mysql_genius-core 0.4.0 first and then
mysql_genius 0.4.0 to rubygems.

spec.files used git ls-files filtered only on ^(test|spec|features)/,
which meant every release of the mysql_genius gem was bundling a
dormant copy of the entire gems/mysql_genius-core/ subtree (47 files,
~150KB) into its package. Those files aren't on the gem's
require_paths (["lib"] only), so nothing broke at load time — it was
just dead weight shipped in every release and a drift-reading hazard
for downstream users who might think the bundled copy is live.

mysql_genius-core is published as its own gem now; the adapter picks
it up as a normal runtime dependency.

Verified: tar -tzf mysql_genius-0.4.0.gem shows 0 files under gems/
after the fix, down from 47.