Fix C01 C05 C09 C14 live qualification harness

[KeyffMS]

Summary

Fixes the four run #5 capability outcomes that were blocked by qualification-harness setup rather than by the Codex 0.152.0 runtime contract.

C01 — repository skill discovery

• seeds a real repository skill under .agents/skills/fixture-capability/SKILL.md outside the model sandbox;
• creates a tracked nested working directory;
• runs explicit activation both from repository root and nested cwd in read-only mode.

C05 — immutable reviewer handoff

• creates a real immutable bundle plus recorded bundle digest and named artifact hash;
• exercises fresh, stale-target, changed-bundle, missing-bundle, and escaped-path cases separately;
• makes the previously missing stale-bundle rejection auditable.

C09 — checkpoint / compaction / recovery

• installs the actual PlanAnvil distribution into the disposable fixture;
• creates a real PlanAnvil planning run and schema-valid generation checkpoint before Codex starts;
• configures model_auto_compact_token_limit to trigger genuine Codex auto-compaction;
• wraps the real PreCompact/PostCompact/SessionStart hooks only to record structural invocation evidence while preserving their output and return code;
• requires two real compaction/recovery cycles and prohibits direct hook invocation or simulated events.

C14 — planning worktree isolation

• installs PlanAnvil into a separate disposable source Git repository under the qualification worktrees auxiliary writable root;
• runs the real plan_anvil.py start controller against that repo;
• verifies source branch/HEAD/index/status/source sentinel remain unchanged while a distinct planning branch/worktree is created;
• does not disable the Codex sandbox or use danger-full-access.

Scope

Only C01, C05, C09 and C14 are overridden. C02 and C13 remain untouched because run #5 may represent real Codex behavior drift and must be investigated independently.

The self-hosted Codex qualification workflow remains workflow_dispatch-only and will not run on this PR. Standard PlanAnvil CI is the validation gate before merge.