Enhance server diagnostics, resource limits, and SQL conformance

[ganeshwhere]

This pull request introduces several significant improvements to release management, CI workflows, documentation, and code quality for the project. The main changes include the addition of a release gate workflow and sign-off process, expanded and documented test and release procedures, enhancements to dependency management, and improvements to code correctness and clarity.

Release Management and CI Improvements:

• Release Gate Workflow and Sign-Off:

  • Added a new .github/workflows/release-gate.yml workflow to enforce automated release gate checks, including build, library tests, integration tests, and critical blocker checks.
  • Introduced a release sign-off issue template (.github/ISSUE_TEMPLATE/release-signoff.md) to standardize manual engineering and operations approval for releases.
  • Documented release readiness criteria and procedures in docs/release_gate.md.

• CI Workflow Enhancements:

  • Refactored .github/workflows/ci.yml to split jobs into quality, unit-tests, and integration-tests for clearer separation and caching of Rust build artifacts. CI now runs on both main and staging branches, and sets colorized output for cargo.

Testing and Documentation:

• Expanded Test Registration and Documentation:

  • Explicitly registered all integration test targets in Cargo.toml and documented the integration test policy in docs/testing.md. [1] [2]
  • Added documentation for running and interpreting the SQL conformance suite and its compatibility report artifact. [1] [2]
  • Updated README.md with clear instructions for running tests and release gates.

• Admin Tooling Documentation:

  • Added docs/config_preflight.md and docs/diagnostics_bundle.md to document the use of the new lsmdb-admin tool for config validation and diagnostics bundle generation. [1] [2]

Dependency and Tooling Updates:

• New Binaries and Dependencies:
  • Registered the new lsmdb-admin binary and its required dependencies (tokio-rustls, rustls-pemfile) in Cargo.toml. [1] [2]

Code Correctness and Quality:

• Catalog and Executor Improvements:
  • Improved error reporting and key handling in src/catalog/mod.rs for better clarity and correctness. [1] [2] [3] [4]
  • Updated executor logic in src/executor/delete.rs and src/executor/filter.rs to use ExecutionContext checkpoints for better resource management and error handling. [1] [2]

MVCC and Durability Documentation:

• MVCC Durability and Modes:
  • Expanded docs/mvcc.md to clarify MVCC durability contracts, crash semantics, and the distinction between in-memory and durable modes. [1] [2] [3]

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Most Important Changes:

Release Management & CI:

• Added a release gate workflow (.github/workflows/release-gate.yml) and a release sign-off issue template to enforce both automated and manual release readiness checks. [1] [2]
• Refactored CI workflows to separate quality, unit, and integration tests, with improved caching and branch targeting.

Testing & Documentation:

• Explicitly registered integration test targets in Cargo.toml and documented the integration test registration policy in docs/testing.md. [1] [2]
• Added and updated documentation for config preflight checks, diagnostics bundles, SQL conformance, and release gate procedures. [1] [2] [3] [4]

Dependency Management:

• Registered the new lsmdb-admin binary and added related dependencies for TLS support. [1] [2]

Code Quality:

• Improved error handling and key usage in catalog operations and enhanced executor logic for better resource and error management. [1] [2] [3] [4] [5] [6]

MVCC Durability:

• Clarified documentation on MVCC durability, crash semantics, and operational modes in docs/mvcc.md. [1] [2] [3]