feat: expand thread calls inline

[douglasmonsky]

Summary

• replace the single-call Threads inspector workflow with inline, row-click expansion
• progressively load and virtualize all calls for the open thread, with retry-safe paging and deep-link restoration
• add concise thread evidence, explicit call actions, responsive layouts, keyboard/ARIA support, and synthetic documentation screenshots
• remove legacy inspector-only analysis code and align browser smoke coverage with responsive table/list presentations

Why

The Threads tab previously opened one representative call when a thread row was selected. That made it difficult to understand a thread as a complete work unit or move between its calls without leaving the thread surface.

Impact

Clicking a thread row now expands its calls in place. Only one thread is open at a time; calls load progressively and remain virtualized for large threads. Opening Call Investigator is always an explicit child-call action, while table, frontier, and lifecycle selections remain aggregate-first.

Validation

• codex-task dashboard-verify --json — PASS (98 test files, 463 tests; lint, typecheck, governance, source budgets, and production bundle)
• npm run dashboard:smoke — PASS (20/20 desktop and mobile Playwright scenarios)
• python scripts/check_release.py — PASS
• git diff --check — PASS
• synthetic dashboard screenshots regenerated and mirrored into packaged docs assets

Notes

• The implementation received an independent whole-branch review; all important and minor findings were resolved before publication.
• Dashboard content remains aggregate-first; no raw session content or private usage data is embedded in generated assets.