Refactor: Fix unwrap issues, dynamo pagination loops, and enforce CLI validation

[subbareddypalagiri]

Hey team! This Pull Request bundles a few structural backend improvements and cleanups:

1. Replace unwrap() with expect() in lore/build.rs

This is a small refactor, but it ensures that if the build script ever fails (for example, missing OUT_DIR environment variables), it will provide a clear, actionable error message rather than a generic panic.

2. Fix Degenerate DynamoDB Pagination Query Bug

Currently, combining Select::Count with a limit in paginated queries causes DynamoDB to fetch the total count one row at a time, resulting in a degenerate performance loop. This adds a strict guard clause to query_paginated to panic/fail-fast if this combination is used, protecting cloud resources.

3. Remove Legacy ENABLE_QUERY_PAGINATION Tech Debt

Pagination support has been stable for some time. This removes the legacy environment variable check (ENABLE_QUERY_PAGINATION) and its associated TODO(jcohen), hardcoding the pagination logic to always run and reducing technical debt.

4. Mutually Exclusive CLI Logging Arguments (Closes UCS-12558)

Resolves the open Jira ticket TODO(UCS-12558): Cleanup logging args. The CLI previously allowed contradictory logging arguments (e.g. running with --debug and --silent simultaneously). This adds conflicts_with_all bounds to the clap parser for level, debug, and silent to strictly enforce mutually exclusive input validation.

This is my first major contribution here, looking forward to any feedback!

[ragnarula]

A panic is not an appropriate way to handle this. This should either be a combination that's structurally not possible and verified at compile time or it should be a properly handled runtime error.

[mjansson]

I would prefer if these unrelated changes are all broken up into separate PRs (and don't forget the DCO sign-off, see the contributing doc for instructions)

[subbareddypalagiri]

Thank you both @ragnarula and @mjansson for the thorough review and constructive feedback! You are completely right on all points.

I have gone ahead and addressed your concerns:

1. Error Handling: I removed the panic!() in dynamodb.rs and replaced it with a proper Result::Err using aws_sdk_dynamodb::error::SdkError::construction_failure so that the server fails gracefully on pagination limit conflicts.
2. Separation of Concerns: I completely tore down this massive PR and broke the 4 unrelated fixes into their own targeted, hyper-focused Pull Requests.
3. DCO Sign-offs: I have ensured that all the new commits are properly signed off (Signed-off-by) to comply with the project's contributing guidelines.

To keep the history clean and to respect your workflow, I will be closing this tangled PR now in favor of the new, separated ones.

Thanks again for your time and for maintaining this awesome project!

Best regards,
Palagiri Subba Reddy