feat(vscode): make graph exploration trustworthy and polished

[forhappy]

Context

Historical graph responses could arrive out of order and replace presentation
state for a newer selection. Revision builds also lacked explicit
cancellation/failure recovery, and architecture/call-graph list limits silently
hid loaded results.

The graph inspector also split source evidence and navigation across duplicate
controls, connected-node colors read as heavy selection rails, and the call
graph opened with an unbalanced top-left resolver sentence and no recovery
surface.

Changes

Trust and correctness

• Make the history webview the controlled authority for selected-commit graph,
  comparison, counts, community, build, and operation state.
• Reject stale revision-bound responses and show the accepted short commit
  beside every visible historical graph.
• Round-trip realization/fingerprint identity with community requests so late
  load completion order cannot corrupt drilldown.
• Add explicit requesting, running, succeeded, failed, and cancelled build
  transitions; cancel active work when the panel closes; bound user-facing
  failures; and route JSONL validation failures through the command promise.
• Keep operational failures beside revision actions and separate from semantic
  findings.
• Disable unavailable parent comparisons with recovery guidance.
• Disclose the 24-flow and 20-continuation initial limits with counts and Show
  all actions.
• Show call-graph node/edge counts and an explicit partial-results alert when
  the contract is truncated.

Inspector and loading UX

• Make the Source metadata card the single source-navigation action, with an
  External Link icon and exact line or byte range in its visible and accessible
  labels.
• Preserve file-only metadata without presenting a false action, and show
  Not recorded when no source exists.
• Replace connected-node color rails with compact community-colored dots.
• Reuse Compass's centered, theme-aware, reduced-motion constellation while
  resolving the function under the editor cursor.
• Add call-graph-specific progress phases and recoverable Retry / Show Compass
  output actions.
• Gate root and expansion responses by resolution generation so superseded
  requests and disposed panels cannot overwrite fresh state.

Validation

• npm run typecheck:js
• npm run test:js — 22 viewer unit tests, 33 extension unit tests, and 27
  Playwright tests passed, including accessibility and performance coverage
• npm run build:viewer
• npm run build:vscode
• npm run test:integration -w editors/vscode — 1 extension-host integration
  test passed
• npm run package -w editors/vscode
• npm run smoke:vsix -w editors/vscode
• git diff --check
• Independent final code review: no Critical or Important findings

Scope boundaries

• No Compass CLI query-limit changes.
• No serializer or graph-contract limit changes.
• No runtime output-path changes; Compass artifacts remain under
  compass-out/.
• Generated graphify-out/, compass-out/, VSIX, and other local output
  directories are not committed.