TST-21: Expand demo director reporting, assertions, presets, and soak follow-through

[Chris0Jeky]

Context

Tracked by: #329

The current demo/director stack is strong enough to prove seeded scenarios, but the MVP expansion sources preserved a second layer of harness maturity work that should remain visible after the historical #297 to #302 migration and the completed #311 audit pass.

Sources:

• docs/InReview/MVP_EXPANSION/MINIMAL/04_SCENARIO_MATRIX_AND_TEST_PLAN.md
• docs/InReview/MVP_EXPANSION/MINIMAL/06_PRIORITIZED_BACKLOG.md
• docs/analysis/2026-03-07_mvp-expansion-source-coverage-audit.md

Depends on

• [Batch E] Integrate and harden migrated demo tooling (merge cleanup, docs, CI policy) #302

Coordinates with

• Post-#297 demo epic audit hardening and coverage expansion #311 as the completed demo-epic audit hardening pass
• TST-20: Product first-run smoke and launch-criteria guardrail #328 for first-run smoke/launch-criteria overlap

Scope

• Add a static/shareable HTML demo report over the existing artifact bundle.
• Add snapshot assertions and trace assertions for high-signal demo/runtime quality checks.
• Add director narrative presets for common proof modes.
• Add long-run soak-mode support for extended autopilot/demo-runtime stress validation.

Acceptance Criteria

• Demo artifacts can be reviewed through a shareable report instead of only raw files.
• Snapshot/trace assertions can fail loudly on meaningful demo-runtime regressions.
• Common director proof modes can be launched through named presets.
• A long-run soak path exists for deliberate runtime stability investigation.
• The work builds on the delivered director stack instead of reopening the migration epic.

Verification

• cd frontend/taskdeck-web; npm run demo:director:smoke
• cd frontend/taskdeck-web; npx vitest --run
• cd frontend/taskdeck-web; npx playwright test --grep "director|demo|artifact"

Suggested branch

• test/demo-director-reporting-and-soak