✨[Feat] Sprint 14 Image Compressor

[maruson08]

Summary

• add a production Image Compressor for JPEG, PNG, and WebP
• default to Original format with explicit JPEG, PNG, and WebP output choices
• apply numeric 50–100% quality to JPEG/WebP while truthfully re-encoding PNG without a fake lossy-quality setting
• preserve oriented pixel dimensions and established alpha behavior

Compression metrics

• report original size, result size, byte difference, and signed percentage change per file
• report aggregate batch totals
• keep and clearly label outputs that become larger
• invalidate stale metrics when files or settings change

Batch and architecture

• process sequentially with shared validation, orientation-aware decode, canvas encoding, safe Unicode naming, ZIP packaging, and save helpers
• save one image directly or multiple outputs as compressed_images.zip
• release decoded sources, reset canvases, and avoid retaining output Blobs in UI state across repeated jobs

Privacy, localization, accessibility

• processing remains browser-local with strict CSP and no upload, analytics, telemetry, CDN, external font, remote module, or runtime network API
• add English, Korean, Japanese, Spanish, German, and French copy with key/placeholder parity
• provide labeled keyboard-operable controls, live status/progress, semantic result metrics, and narrow-screen stacking

Validation

• node tests/run-all.mjs passes, including Compressor, Converter, Resize, all PDF regressions, localization, accessibility/responsive, security, CSP, and network audits
• git diff --check passes
• bounded browser QA was attempted, but the known Windows browser bridge ACL failure occurred before rendering; no visual QA claim is made

Deferred

• target-size search, iterative optimization, resize/crop/filter workflows, metadata tools, new codecs, and server features remain out of scope

PR targets v2. main remains untouched.