feat(desktop): present thread work reports first

[contentscoin]

Summary\n\nStacked on #7057. Review only the top commit 5483ade until #7057 merges; GitHub will automatically shrink this PR to the Desktop-only delta afterward.\n\n- validate and reduce thread-rooted kind:40009 work reports\n- fetch the current report and invalidate it from a live channel/thread subscription\n- present the signed result before the transcript\n- collapse the conversation by default while preserving one-click access to evidence\n- cover parsing/head selection and the real Result Card browser flow\n\n## Local verification\n\n- targeted reducer tests: 5/5 pass\n- pnpm typecheck: pass\n- E2E production build: pass\n- Result Card Playwright smoke: 1/1 pass\n- Desktop full unit suite: 5803/5804; the sole useDocumentVisible focused-polling timing failure reproduces in isolation and is outside this diff\n\nThe fork PR runs the repository-wide CI gate. This PR remains draft until that run and independent review pass.

[github-actions]

🔐 Codex Security Review

Status: review required for the current range.

The current range is eed74bde2f4797714335ac10c56c0b0244c1def4...03c24dc811c8c92123e0974d03b2ff7da57e7f68.
A new review must complete for this exact range. When manual authorization
is required, a Block organization member must comment exactly
@buzz-security-review 03c24dc811c8c92123e0974d03b2ff7da57e7f68 to authorize a new review.
Any previous review applies only to its recorded range.

[contentscoin]

Independent review passed the Desktop top commit. Follow-up 03c24dc adds the report signer avatar/name, preserves an already-visible conversation when a report arrives live, and aligns hex-id ordering with the CLI. Local typecheck, reducer tests (5/5), E2E build, and Result Card Playwright (1/1) pass. The new fork CI run on this head is the final code gate.

[contentscoin]

Maintainer review requested. The stacked Result Card PR is now ready: fork CI run 33322977445 completed successfully at head 03c24dc, including Desktop Core, macOS build, relay/integration E2E, and all four smoke shards. An unrelated sidebar snapshot timing failure on the first attempt passed when the failed shard was rerun. Independent review passed, and the requested signed-author display, initial-collapse preservation, and deterministic ID tie-break fixes are included. This PR remains stacked on #7057 and should merge after it.