refactor: enforce dashboard query pipeline contracts

[douglasmonsky]

Summary

• retire request-time recommendation fallback in favor of indexed materialized facts
• enforce registered frontend query/schema contracts and deterministic route budgets in CI
• self-heal bounded recommendation-fact gaps and preserve incremental thread-summary refreshes
• bound and cache investigation queries, including large low-output, repeated-file, and shell-churn reports
• rejoin active Compression Lab jobs and retry cleanly across usage-index writer contention
• default automatic refresh on while pausing it on evidence-heavy views
• show estimated dollar cost first on Overview while retaining estimated credits
• stabilize the 40% persistence speedup ratchet with a larger five-round sample

Performance

• 100k synthetic allowance diagnostics: 8.321s before, 0.392s cold p95, 0.062s warm p95
• live large-low-output investigation: about 37s before, about 0.61s cold after; generation-stable warm hits are milliseconds
• live incremental refresh after summary fix: about 100s before, 20.5s after on the current large local dataset
• repeated same-scope Compression Lab profile reload: single-digit milliseconds after the first completed run

Validation

• Agent Maintainer full profile: PASS (20260714T191542469371Z-full-d7f5aedf4177)
• dashboard verification: 421 tests, lint, typecheck, governance, and bundle report: PASS
• focused Python integration/query and benchmark tests: PASS
• Tach, Ruff, MyPy, Markdown lint, release check, and diff check: PASS
• live all-history dashboard HTTP and visual verification: PASS

Closes #244.