Release v1.9.2

[stef-k]

Summary

• release Wayfarer v1.9.2
• document per-user idempotency-key convergence for mobile offline-queue recovery imports
• align runtime version documentation and version assertions

Includes the backend recovery support merged in #494 and coordinates with stef-k/WayfarerMobile#244.

Validation

• release helper: passed for v1.9.2
• runtime CLI: Wayfarer 1.9.2
• versioning tests: 26 passed
• Release build: succeeded, 0 warnings/errors
• Vite production build: succeeded
• ordinary non-browser suite: 2,347 passed, 150 opt-in PostgreSQL skips, 0 failed
• LOC policy: passed; pre-existing warnings only
• git diff --check: passed

Validation debt

• Provision deterministic Chromium for .NET Playwright rendering test #415 reopened: local .NET Playwright screenshot capture currently fails after real Chromium launch
• Fix detached API user ownership in PostgreSQL clone fixture #495 opened: guarded PostgreSQL clone fixture reattaches an already-persisted API user
• neither failure is in the four-file release-only range; the exact PR-head GitHub test check remains the merge gate

Database

No migration. The included #494 implementation reuses the existing nullable idempotency-key column and per-user unique index.