verify: misleading error when a report contextFiles path escapes the repository

[aryamthecodebreaker]

Found while stress testing the CLI on Windows (v0.9.0, built from main).

Steps to reproduce

1. Generate a report: fixmap plan --issue "reset token ttl" --repo examples/tiny-auth-app --format json --output out.json
2. Edit contextFiles[0].path to a traversal path, e.g. ../../evil.ts (everything else untouched)
3. Run: fixmap verify --report out.json --repo examples/tiny-auth-app --working-tree

Actual

"out.json" has an invalid contextFiles entry at index 0; each entry needs a non-empty string "path", and
version 1 requires rank, score, confidence, and reasons fields with their documented types.

Expected

All field types are valid - the real problem is that the path escapes the repository root. The error should say something like:

"contextFiles[0].path must stay inside the repository (got "../../evil.ts")"

For comparison, changing the path to a benign non-existent file (src/other.ts) is accepted and verify proceeds normally, which confirms the type-check is not what is failing.

Why it matters: hand-edited or third-party-generated reports are a supported workflow (verify exists precisely for that), and this message sends users hunting for a schema problem that does not exist.