refactor(commands): extract shared embedding core

[lfnovo]

Summary

Deduplicates commands/embedding_commands.py (and the thrice-copied full_model_dump). Pure refactor — behavior-identical: same outputs, same success=False paths, same log messages, same retry configuration.

• Shared embed core: embed_note / embed_insight / embed_source were structural clones (load → validate → embed → UPSERT + an identical ~20-line ValueError/Exception epilogue ×3). They now run through one _embed_record(...) runner holding the epilogue; note and insight additionally share _embed_markdown_record(...) for their identical bodies.
• Rebuild loop unified: rebuild_embeddings_command submitted jobs via three copy-pasted loops — now one _submit_embedding_jobs(kind, command_name, id_field, ids) helper (same progress/error log messages).
• Shared retry config: the four embed-family commands reuse a single EMBED_RETRY_CONFIG dict. Added a # NOTE: marking that stop_on: [ValueError, ...] can never trigger today (commands catch ValueError internally and return success=False) — intentionally preserved as-is for a future error-handling PR.
• full_model_dump(): was copy-pasted in embedding_commands.py, podcast_commands.py and source_commands.py, but only podcast_commands actually used it. Moved to open_notebook/utils/model_utils.py (exported from open_notebook.utils), imported in podcast_commands; the two dead copies were removed rather than re-imported (F401 is enforced again as of chore(lint): re-enable F401/F841/E722 and fix fallout #1062).

Line delta: +232 / −319 overall; embedding_commands.py alone drops from 799 to ~636 lines.

Verification

• uv run pytest tests/ — 403 passed
• ruff check . — clean; ruff format — clean
• uv run python -m mypy commands/ open_notebook/utils/ — 8 pre-existing errors, identical count and locations as main (none in touched lines)
• Import smoke test: import commands registers all 8 commands with retry configs identical to main (verified via the surreal-commands registry)

[cubic-dev-ai]

No issues found across 6 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

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