fix(example): report supported image formats and failed loads accurately

[OskarEichler]

Fixes

Use image/jpeg for native/Windows JPEG previews, restrict the legacy webm option to Android, remove the unsupported web pixelRatio option, show the actual output format/quality and clear old format previews, and report failed cross-origin image loads instead of waiting indefinitely.

Compatibility / observable changes

Example-only corrections. No API, dependency, layout or styling changes. Failed remote images keep capture disabled and expose a polite live status; a later successful load restores normal capture.

Verification

Ten actual React-rendered checks pass across native, Windows and web examples; eight fail on the baseline. Checks cover MIME, platform-specific format cycling, supported capture options, preview metadata/reset, and failed/successful image event controls. No assistive-technology or full Windows rendering claim.

This patch was applied independently to upstream commit 6acbec50a5e3cab7d668711d757c52cfdc791c76 and passed its targeted external actual-source diagnostics. Across the focused patches, 119 such checks pass. Java/Objective-C diagnostics use controlled bridge/platform doubles or owned filesystem fixtures; they are not substitutes for physical-device rendering tests.

Combined branch checks:

• Existing JS suite: 4 suites, 46 tests pass.
• TypeScript, ESLint (zero warnings), full Prettier check and library build pass.
• Existing Android unit suite: 62 tests pass; Android Debug example build passes.
• Existing Windows managed helper suite: 16 tests pass on .NET 8.
• Unsigned iOS Simulator example build passes. Native tests: 13/14 pass; the one intentional old-behavior assertion conflict is described below.
• Android and iOS production Metro bundles pass. Web production build passes with three bundle-size warnings.
• React 18.3.1: all 21 applicable JS diagnostic controls pass; React 19 includes callback-ref cleanup coverage.

The separate iOS cleanup patch intentionally makes the existing test named testReleaseCapture_currentlyDeletesPrefixOnlyImposterDirectories_KNOWN_LOOSE_GUARD fail because it asserts the unsafe old behavior. That patch is kept in a separate draft PR. No checked-in test/spec or snapshot files were added, modified, regenerated or disabled.

Windows/Expo native builds, physical-device video/PixelCopy output, and full Detox suites were not run. The full unchanged Playwright suite was run against both baseline and patched builds: both have 9 passes and the same 3 failures. Two Linux-reference screenshot mismatches have byte-identical baseline/patched actual images on macOS. The CORS fixture hard-codes port 3000, occupied by an unrelated local backend; the isolated example uses another port. No snapshots or assertions were changed. React Doctor also reports existing example suggestions and a React-18 ref-cleanup warning; the latter was checked against actual React 18 legacy-ref and React 19 cleanup behavior. No rules were suppressed.

Scope

• example/src/screens/ImageTestScreen.tsx
• example-windows/src/screens/ImageTestScreen.tsx
• example/src/screens/FSTestScreen.tsx
• example-windows/src/screens/FSTestScreen.tsx
• example-web/src/screens/ImageTestScreen.tsx
• example-web/src/screens/CORSImageTestScreen.tsx

Unrelated audit changes are submitted separately.