feat: add git-aware memory ingestion and validation

[GautamSharma99]

Closes #147

Summary

This PR adds Git-aware memory workflows that bootstrap Greplica from repository history and detect claims whose code anchors become
stale after code changes.

What changed

Git history ingestion

Adds:

greplica git ingest
[--max-commits ]
[--max-age ]
[--prs]
[--github-token ]
[--dry-run]

The command:

• Collects commit metadata and changed files using a single git log call.
• Extracts claims from conventional commits and decision/requirement language.
• Generates deterministic components from changed modules.
• Detects recurring module co-changes and creates flows using statistical lift.
• Creates a git_history source for every analyzed commit.
• Optionally enriches sources with GitHub PR metadata.
• Deduplicates generated objects against existing graph memory.
• Supports previewing the generated proposal with --dry-run.

Continuous anchor validation

Adds:

greplica git watch
[--daemon]
[--once]
[--interval ]
[--anchor-threshold ]

The watcher:

• Polls the repository HEAD for new commits.
• Persists the last processed HEAD and full-audit timestamp.
• Validates only claims touching changed files after a commit.
• Periodically performs a complete anchor audit.
• Reuses the existing tree-sitter resolver and stored anchor fingerprints.
• Falls back to a full audit when a previous commit range cannot be resolved.
• Avoids creating duplicate review relationships.

New graph vocabulary

Introduces:

• insight claim kind for automatically extracted knowledge.
• git_history source kind for commit provenance.
• needs_review edge kind for claims with potentially stale anchors.

Review edges include a reason:

• file_deleted
• symbol_removed
• file_content_changed

Proposal validation rejects new relationships that reference claims needing review. supersedes relationships remain allowed so stale
claims can be replaced.

Graph view

The graph view now:

• Displays warning icons on claims needing review.
• Adds a “Claims - Needs review” filter.
• Distinguishes Git-history sources from session and code sources.
• Includes insight claims in claim-type charts.

Testing

Added an end-to-end test that:

• Creates a temporary Git repository with conventional commits.
• Verifies claim, component, source, and co-change flow extraction.
• Seeds a fingerprinted, code-verified claim.
• Commits a behavioral change to its anchored file.
• Confirms the watcher detects the changed file.
• Confirms a needs_review edge is created with the correct reason.
• Confirms proposals referencing the stale claim are rejected.
• Confirms redundant checks at the same HEAD are skipped.

Graph-view tests were also expanded to cover Git-history sources, insight claims, warning indicators, and review filtering.

Validation

• npm test
• npm run typecheck
• git diff --check

All checks pass against the latest main.