Sprint 15.3 — Implement Image Metadata Inspector UX

[maruson08]

Problem / motivation

Users need an honest, accessible view of supported image metadata without uploading or decoding pixels.

Scope

Implement single-file replacement input, source/container summary, localized inspection coverage, non-empty metadata groups, diagnostics, no-supported-metadata state, and safe text rendering.

Non-goals

No batch queue, image preview, Canvas, maps, reverse geocoding, raw binary dump, or exhaustive-privacy claim.

Acceptance criteria

• JPEG/PNG/WebP inspection works for one source at a time.
• metadata-partial is presented as successful but non-exhaustive.
• Opaque detected payloads are not shown as empty.
• Untrusted metadata and diagnostics use textContent only.
• Keyboard, live-region, responsive, theme, and reduced-motion contracts pass.

[maruson08]

Completed by PR #29, merged into the v2 integration branch at 82f09e8. GitHub did not apply the closing keyword automatically because v2 is not the repository default branch.