Fix AI widget rendering and automate visual quality review

[everettjf]

AI-generated widgets could pass runtime validation while showing invisible light-mode text, clipped rings or an incorrectly narrow iPad preview. This fixes those rendering issues and adds a repeatable way to inspect generated widgets before release.

• Capture native appearance before JavaScript worker execution; macOS no longer reports dark mode unconditionally.
• Support documented numeric/single-string square frames, rejecting boolean, negative and non-finite values; align extra-large preview dimensions with the generation prompt.
• Improve generation guidance for contrast, spacing, chart axes and requested data. Refresh DeepSeek presets using the service's current model list.
• Add an opt-in eight-case generation matrix, light/dark native snapshots, component/text checks, local Vision OCR, offline HTML reports and zero-API replay. Update frame completion metadata, generated docs and both editor bundles.

Validation: DeepSeek flash baseline and improved runs each produced 16/16 renderable samples. The improved samples passed expected-text/component checks; all 32 improved screenshots were manually reviewed. A separate 16-case offline replay passed. This is bounded smoke coverage, not a universal visual-quality score. Before/replay/after screenshots and reports remain local under __Release/ai-quality/2026-09-22/.

Local validation:

• ./Scripts/release-readiness.sh passed: 29 editor tests, 164 macOS tests, 166 iPhone simulator tests; app builds passed.
• ./Scripts/ipad-icloud-tests.sh passed: 166 iPad Pro simulator tests.
• AI_QUALITY_REPLAY=... AI_QUALITY_OUTPUT=... ./Scripts/ai-quality.sh
• Metadata, documentation links and git diff --check passed. The normal suites skipped 7 macOS / 6 iOS tests requiring opt-in live services or signed iCloud.

Security/compatibility: no new permissions, dependencies or credential storage. Live tests are opt-in and use synthetic offline prompts; no user widgets are sent. Credentials and generated artifacts are excluded from the PR. Square-frame behavior is additive; existing width/height forms are preserved. Physical WidgetKit/Live Activity, signed iCloud containers and Apple PCC calls were not tested in this round. No App Store submission is performed.