Fix ~790 basedpyright errors across the test suite:
- Type stub subclasses of real production classes with super().__init__()
- Add missing generic type arguments and Dict[str, Any] annotations
- Add None guards before subscript/member access
- Adapt tests to production API changes (removed dead handlers,
PersistentModelCache.get_default, _i18n_filter_added location)
- Update CSP whitelist to use wildcard *.civitai.com for all CDN subdomains
- Fix hostname parsing to use parsed.hostname instead of parsed.netloc (handles ports)
- Update rewrite_preview_url() to support all CivitAI CDN subdomains
- Update rewriteCivitaiUrl() frontend function to support subdomains
- Add comprehensive tests for edge cases (ports, subdomains, invalid URLs)
- Add security note explaining wildcard CSP design decision
Fixes CSP blocking of images from image-b2.civitai.com and other CDN subdomains
