feat(maintainer): stabilize MR lifecycle, finding triage, and discussion closure

[Windsander]

Summary

This PR improves the stability of the Maintainer workflow for long-running merge requests with many CI reviews, findings, and Discussion updates.

It focuses on preventing repeated replies, stale finding processing, stalled repair loops, and incomplete Discussion closure without rewriting the existing framework.

What Changed

• Added explicit MR lifecycle state handling and MrLifecycleMetrics for repair, explanation, suspension, and follow-up outcomes.
• Improved structured CI Review recognition and finding extraction.
• Filtered statistical-only reports so they do not trigger unnecessary repair attempts.
• Added stale finding checks for deleted files, moved lines, outdated baselines, and already-fixed evidence.
• Improved the no-progress path so Maintainer re-evaluates whether an issue has already been fixed before asking for clarification.
• Stabilized Discussion pagination and interaction-based windowing, preserving Discussions that have recent replies or updates even when the total note count exceeds the window.
• Added safer reply deduplication, backfill throttling, per-finding explanations, and resolve handling.
• Improved repair-loop diagnostics and final acting rounds to avoid repeated read-only exploration.
• Added commit-pipeline handling for project-specific commit-message hooks and validation failures.
• Connected Maintainer lifecycle outcomes and repair decisions to the EverOS project memory system.
• Added realistic MR replay coverage and sanitized test fixtures to remove real project paths, local absolute paths, and prohibited branding.

Behavior Improvements

Maintainer can now:

• Distinguish actionable findings from summaries, praise, and pure statistics.
• Avoid repeatedly commenting on findings that are already fixed or already explained.
• Continue processing later Discussions instead of remaining on the first few items.
• Explain why each finding does not require a change before resolving it.
• Recover from project-specific commit hook failures when the required format can be inferred from the hook output.
• Preserve valid Discussion activity outside the initial note window.

Validation

• Full Vitest suite passes.
• Maintainer replay, ask-gate, and commit-pipeline tests pass: 34/34.
• tsc --noEmit passes.
• Fixture JSON parsing and Prettier checks pass.
• git diff --check passes.
• RULE compliance audit passes.
• Historical test fixture audit confirms no real project paths or prohibited branding remain.

Scope

This change is intentionally focused on Maintainer lifecycle behavior, repair safety, Discussion processing, and EverOS memory integration. It does not rewrite the framework or change the existing Reviewer/Archiver architecture.