fix(producer): reject asset media type mismatches

[jrusso1020]

Summary

• Classify localized local assets from ffprobe streams and container signatures, including extensionless media, AVIF, multiple video streams, attached cover art, and structurally complete PNG fallback.
• Fail image, video, and audio element mismatches early with stable ASSET_MEDIA_TYPE_MISMATCH metadata.
• Preserve missing, corrupt, remote-at-runtime, and unprobeable assets on their existing downstream error paths.
• Run preflight after static compilation and again after browser reconciliation so the known videoCount=0 image-probe case is covered.

Ownership and retry policy

Deterministic media-type mismatches are owner=user and retryable=false. Error transport is allowlisted and bounded; raw source URLs and paths are never included.

Validation

• Targeted media profile and preflight suites: 50 passing.
• Full engine suite: 1,240 passing, 3 skipped.
• Full producer unit lane: 464 Vitest tests plus all Bun unit files passing.
• Full producer integration lane: all Vitest and Bun integration files passing.
• Pre-commit lint, format, fallow, and typecheck gates passing; the final documentation-only follow-up used a manual clean tracked-artifact check because the sandbox denied the hook subprocess.
• Independent adversarial review: no blockers.

Scope

HDR behavior and hyperframes-internal dependency or version changes are intentionally out of scope.

Rollback

Revert this PR (commits 01a55be and 124b4ab). No migration or persisted state is introduced.