Comment cleanup pass on biometric-vault package

[LiranCohen]

Summary

The biometric-vault package has accumulated ~700+ comment lines that reference internal review iteration (Round-N FX: prefixes), narrate pre-fix vs. post-fix history, or expand single-sentence intent into multi-paragraph essays. This is noise — git history captures the fix narrative; comments should describe the current code's intent and constraints.

Scope

Files with the highest comment debt:

File	Round-N / pre-fix references
src/lib/enbox/__tests__/biometric-vault.test.ts	70
src/lib/enbox/agent-store.ts	67
src/lib/enbox/biometric-vault.ts	61
src/lib/enbox/__tests__/agent-store.reset-blockers.test.ts	57
android/.../NativeBiometricVaultModule.kt	27
src/features/session/session-store.test.ts	26
src/features/session/session-store.ts	21
ios/.../RCTNativeBiometricVault.mm	16
(long tail across remaining package files)	~200

Problems with the Current Style

• Review-cycle prefixes (// Round-15 F3:, // Round-9 F4:): meaningless to anyone not present for the original review.
• Pre-fix narration (Pre-fix the helper logged a warning and returned 'true'...): explains code that no longer exists.
• Multi-paragraph essays where one sentence would do: many comments restate the surrounding code instead of explaining intent.
• Fictional spec tags (VAL-VAULT-028): there is no validation document the codebase ships; these tags don't resolve.
• self-review tags: internal AI-cycle nomenclature.

Acceptance Criteria

• Zero Round-N FX: / Round-N self-review: prefixes in the package.
• No Pre-fix ... / pre-fix ... historical narration.
• VAL-VAULT-XXX tags either resolve to a real, checked-in spec or are removed.
• File / function header comments describe the what and why (intent, invariants, non-obvious constraints) — not the change history.
• Multi-paragraph block comments collapsed to 1–3 lines unless they capture a non-obvious invariant or trade-off.
• Crash-resilience / fail-CLOSED rationale stays — but framed as current constraints, not as patch notes.
• Test files: prefer descriptive describe / it titles over inline narration; keep at most one short intent comment per test.

Out of Scope

• Refactoring code structure (separate issues).
• Renaming public APIs.

Notes

• Commit messages and PR descriptions remain valid places for review-round nomenclature; they live in git history where it belongs.