refactor: remove dead code and narrative comments

[jacaudi]

Summary

Full-repo /simplify sweep — removes dead code, duplicate helpers, debug artifacts, and narrative comments across 23 files. Fixes one latent bug.

-444 lines net. All 166 Node.js tests + 7 Go tests pass.

Changes by area

Dead code removal

• workers.js — deleted loadWorkerScript, loadWorkerFromBlob, getWorkerScript; collapsed 1-iteration buildWorkers loop and dropped vestigial round-robin worker_pointer (there is always exactly one worker)
• crypto-ops.js — deleted stringToArrayBuffer, leaveItAlone, deselectLastActiveAccount, useBiometricsErrorHandler; collapsed genDefaultSeed IIFE
• renderer.js — deleted html_newShare stub, animated_list, toggleAnimations, destroyAnimations, clear_clipboard
• crypto-storage.js — deleted compressor, clearDatabase, unused cb params
• webauthn.js — deleted empty init() IIFE, dead nested handleBioLogin, duplicated concatArrayBuffers (now uses combineArrayBuffers from crypto-ops.js), redundant webAuthnClick wrapper
• buffer.js (main + worker) — deleted broken convertBufferType (referenced undefined identifier), bufferPush, getBufferTypedArrayConstructor
• worker/index.js — deleted dead state (active_mp_buff, active_pk_buff, active_ecdh_pub_key) and corresponding gen_seed_pk case
• file-import.js — deleted 6× var qq = 22; breakpoint artifacts, dead removeDragEvents, handleDropAnimation
• file-ops.js — collapsed decodeData and parseFilekeyFile identity passthroughs
• worker/encryption.js — deleted dead hexToArrayBuffer
• init.js — removed dead top-level declarations
• Duplicated checkForProperty — 4 copies consolidated into the one in lib/utils.js

Bug fix

• db-handler.js — if (!valid) setPersistentWarning; → setPersistentWarning(); — missing parens meant the persistent-storage warning was never actually emitted when IndexedDB init failed

Documentation hygiene

• Stripped narrative comments from build.js, strip-comments.js, debug.js (main + worker), server/main.go, crypto-ops.js, init.js
• Removed issue-number references (#36, #37, #45) from test strings and inline comments
• Test cleanup: test-infra.js rewritten to hoist shared read, brittle "mentions environment variable" doc assertion removed

Helper relocation

• Moved sanitizeFilename from src/js/ui/file-import.js to src/js/lib/utils.js alongside other string utilities

Deferred

Five higher-risk simplification targets are tracked in #53:

1. ECDH P-521 arithmetic hot paths (needs benchmarks)
2. doStuff / undoStuff unification (behavior refactor)
3. lib/buffer.js build-sharing (structural)
4. get_query_strings rewrite (fragile closure dependency)
5. secureOverwriteBuffer useRandom flag (security-adjacent)

Test plan

• node scripts/build.js && node --test app/tests/test-*.js — 166/166 pass
• Go test suite runs clean in CI
• Grep-verified every delete against the codebase before removing
• Verified load-order for combineArrayBuffers cross-reference from webauthn.js

🤖 Generated with Claude Code