fix: harden sandbox bootstrap and replica materialization

[misrasaurabh1]

Implements deterministic, hash-only idempotency for ambiguous sandbox session exchange with one bounded retry, exact archive-receipt verification, and safe atomic read-only replica materialization.

Unix materialization is descriptor-relative and uses no-follow filesystem operations for extraction, traversal, chmod, rollback, and held-identity no-replace publication. The non-Unix compatibility path retains nested-directory creation. Adversarial component and staging-root substitution tests prove no writes or chmod escape staging.

Also updates Hono and the Cloudflare development toolchain, with a patched sharp override, to resolve current dependency advisories. The mock HTTP server normalizes accepted sockets so retry tests are deterministic on Darwin.

Validation:

• localityd replica materializer: 17/17
• loc-cli sandbox retry suite: 5/5 plus 25 consecutive bounded-retry runs
• OAuth service: typecheck, 15/15 tests, Wrangler 4.113.0, zero npm audit findings
• independent reviewer: no blocker, high, or medium finding through e38ef6c
• Linux ARM64 musl release build installed and SHA-256 verified on the acceptance host
• final GitHub CI matrix rerun in progress after unrelated scheduler timing flakes

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Project	Deployment	Actions	Updated (UTC)
locality	Ready	Preview, Comment	Jul 22, 2026 8:03pm

[github-actions]

Codex review

• minor: apps/oauth-service/package.json:24 declares top-level overrides twice. JSON consumers commonly keep only the last duplicate key, so the newly added "sharp": "^0.35.3" block is silently ignored and tooling that rejects duplicate object keys may fail on this manifest. Minimal fix: collapse this to a single overrides object with the intended sharp constraint.