docs(pilot): record captured matched observation

[akoita]

Closes #397

Summary

• record the explicitly authorized twenty-fourth matched-backend observation from revision 75e288f
• document the single non-retryable Anthropic author failure and absence of artifact or critic review
• record only the bounded protocol result: terminal reason api_error was captured locally; no subtype or underlying cause was established
• keep parity indeterminate and release preparation blocked, with provider classification isolated in fix(provider): classify statusless Claude API-error results #398

Observed boundary

• both 20-second user-session authentication probes passed
• one Anthropic author attempt failed with code unknown, no failure stage/reason, and zero reported tokens
• fixed diagnostics recorded unrecognized subtype/terminal reason, stop_sequence, and capture saved
• no artifact, critic call, review, adjudication, approval, export, submission, or release occurred
• authorization is exhausted

Privacy

The disposable runner and private 0600 capture were deleted. This diff contains no private paths, run/session identifiers, candidate or opportunity content, provider prose, credentials, or private thresholds.

Verification

• pnpm validate
• 104 Vitest files / 1,585 tests passed
• 54 release checks passed

The first unchanged gate reproduced open #389 during file refresh; that exact test passed 1/1 in isolation, and the unchanged full rerun passed.