fix(code-graph): close versioned graph reliability gaps

[forhappy]

Summary

This closure PR hardens Compass Code Graph v1 before it lands through #79.

• make every public, CLI, and MCP graph reader follow the active generation pointer dynamically and fail closed on malformed or incomplete generations
• make fresh AST facts authoritative during incremental node and edge reconciliation while retaining truthful semantic-only evidence
• reconcile moved, deleted, aliased, remapped, and cardinality-changing relationship occurrences deterministically
• canonicalize and validate trusted endpoint rewrites before consuming transient remap proof
• bound source retrieval, query fan-out, aggregate traversal work, and route candidate collection
• close relationship endpoint compatibility and normalize producer output into the typed v1 contract
• preserve atomic generation publication and deterministic cold/incremental output

Why

The earlier implementation passed broad qualification, but independent closure reviews found stale-generation reader bypasses, stale mixed-origin relationship sites, over-broad endpoint validation, route confidence loss, and unbounded work paths. These fixes address the root causes and add focused regressions for each failure mode.

Impact

Versioned graph reads now resolve one complete active generation or fail explicitly. Incremental graphs remain byte-consistent with equivalent cold extraction while accurately distinguishing AST evidence, semantic-only residue, and transient endpoint remaps. Query and source operations have hard resource ceilings, and route and relationship publication remains conservative.

Validation

• independent final review: READY with no Critical, Important, or Minor findings
• ./scripts/qualify_code_graph_v1.sh --fixtures-only
  • workspace formatting and Clippy
  • full all-target Rust workspace tests
  • viewer 94/94 and VS Code 86/86 unit/component tests
  • Playwright 65/65
  • JavaScript typechecks and production builds
• locked polyglot corpus: 29,094 nodes, 49,076 edges, routes 61 exact / 3 ambiguous / 7 unresolved, zero false-exact resolutions
• atomic publication regressions and graphify update .

Exact reviewed head: cd5092237a45bafdc6a9b4588555944c0c0407c1.