Add PRD-style QA scenario slices and AltShift starter scenarios

[Hector-Ha]

What to build

Add versioned QA Scenario Slice support using PRD-like YAML briefs. Scenarios should give agents full test context while the runner parses only safety/routing metadata.

This slice should include starter scenarios for https://github.com/Hector-Ha/AltShift so agents can run focused QA slices instead of one giant checklist.

Acceptance criteria

• QA Scenario Slice YAML lives under est/qa-scenarios.
• Scenario YAML supports id, target repo, allowed actions, blocked actions, network policy, evidence needs, feature/version requirements, and known GitHub issue refs.
• Scenario body supports natural-language brief content for goal, steps, expected behavior, warning signs, manual inspection notes, and edge cases.
• Scenario YAML must not allow arbitrary shell commands or executable hook code.
• Runner requires explicit scenario paths or ids and does not default to running all scenarios unless caller names the full intended set.
• At least the first AltShift scenario set exists, covering clone/analyze, Env Draft inspection, Env Draft save, and known-risk areas from the current roadmap.
• During a QA run, known GitHub issue refs are fetched best-effort when network/auth are available, but lookup failure does not block local QA.
• Tests cover scenario parsing and safety metadata handling.

Blocked by

• Add CLI Chrome-supervised QA runner foundation #30

Notes

Scenario files are agent-readable test briefs, not machine-only assertion lists. Expected product behavior belongs in the scenario brief; actual results belong in the session report.

[Hector-Ha]

Closing as not planned, not resolved.

This issue was created before the QA design finished. The design changed: QA harness/scenarios/evidence should live in private/local .qa-local or a private QA repo, while public InstantRepo should only add production-safe CLI surfaces. This issue mentions public QA runner/internal QA implementation and should not be picked up.

We will create replacement issues after the grill-with-docs design session is complete.