fix(eval): enforce pre-edit fallback route assertions

[Helweg]

Review finding

Independent review of the three latest merged PRs found one functional omission in #257: the unresolved-symbol golden query recorded expectedRoute: "search" and expectedOutcome: "results", but those values were only reported as metrics. The pre-edit budget did not enforce them, so a routing regression could still pass Hit@5/MRR and CI.

Fix

• Add optional minRouteAccuracy and minOutcomeAccuracy budget thresholds.
• Parse and enforce them in evaluateBudgetGate.
• Require both at 1.0 in benchmarks/budgets/pre-edit.json.
• Add unit/schema coverage and document the gates.

Validation

• npm audit --audit-level=moderate reports 0 vulnerabilities.
• Focused eval suites pass: 46 tests across budget, schema, and metrics.
• npm run typecheck and npm run lint pass.
• Independent end-to-end pre-edit mock-embedding gate passes with no violations: Hit@5 1.0, MRR@10 1.0, graph-neighbor recall 1.0, route accuracy 1.0, outcome accuracy 1.0.
• npm run build passes. The full local test run retained four known environment-sensitive timing failures in unrelated identity/watcher tests. The changed eval suites pass in isolation and the prior merged PR checks were green.