fix: address final code review feedback for mobile claim flow
- Fix ClaimSuccessScreen pdsEndpoint extraction: Use PLC directory format (services map with atproto_pds.endpoint) instead of W3C format (service array with serviceEndpoint). Previously always showed '--'.
- Fix DIDDocumentScreen format mismatch: Add normalizePlcDocToW3c() function in +page.svelte to convert stored PLC format DID documents (services map, rotationKeys array) to W3C array format (service array, verificationMethod array) before passing to DIDDocumentScreen for viewing stored identities.
- Fix IdentityListHome badge visibility: Remove conditional that hid badge when deviceKeyIsRoot is null. The badge with 'Unknown' label and gray styling already exists in getBadgeLabel and CSS, so badge should always be shown.
- Create shared PDS extraction utility: Extract duplicate PDS extraction logic into new did-doc-utils.ts with extractPdsFromPlcDoc() function. Use it in both IdentityListHome and ClaimSuccessScreen to reduce code duplication.
All changes verified: build passes, type check passes (0 errors, 0 warnings).