feat(reliability): recover local fleet operations [skip-bump]

[zaydiscold]

Summary

Recovers the local Hydra improvements on top of current master without changing the published version or triggering release automation.

• improve session refresh, dashboard recovery, account and code flows
• strengthen CLI operations, redaction, and cancellation handling
• add focused regression coverage for batch work, signup boundaries, background failures, and CLI behavior
• document the previously missing 1.6.2 fleet-reliability release
• pin Prisma 6.19.3 in the lockfile and manifest

Safety

The repaired scripts/recon/check-all-sessions.mjs was intentionally excluded. PR #67 removes it as unsafe public diagnostic tooling.

Verification

• npm run lint passes with one existing React hook-dependency warning
• npm run build passes
• npm run test:batch-runner passes, 6 tests
• npm run test:clerk-signup-boundary passes, 2 tests
• npm run test:background-failure-visibility passes, 36 tests
• npm run test:cli passes, 51 tests

The Prisma-backed CLI test was run with RUST_LOG=debug because this machine has an inherited RUST_LOG setting that causes Prisma to emit an empty schema-engine error. This is a local environment issue, not a test failure.