Fix Google Photos pagination & high-res portraits (closes #155)

[starbrightlab]

Cherry-picks @miguelsg29's Google Photos fix (8a31dec, originally in #164) onto a clean branch off main, decoupled from the Spanish i18n sweep so it can land on its own. Authorship preserved.

What it does (closes #155)

• Pagination: crawls the Google Photos shared-album batchexecute RPC (extractGoogleAlbumKey / extractGoogleContinuationToken / fetchGoogleBatchRpc in RemoteAlbum.kt) so albums with >30 photos load beyond the initial HTML chunk (hard-capped at 100 pages / 10k photos).
• High-res portraits: CDN suffix =w{maxDim}-h{maxDim}-no at max screen dimension; aspect-preserving background blur, dual-layer crossfade, clipped Ken-Burns frame, and an opt-in cropVertical toggle (added as a BoolSpec, tripwire-clean).

Review notes (from deep review)

• Fails safe: every new path returns page-1 results or falls back to the built-in feed on error, so it can't regress today's behaviour.
• ⚠️ Pagination is best-effort: the continuation-token regex leans on undocumented Google internals and may not match the real cursor for every album, so the "~30-photo cap" symptom could persist in the field for some albums and will rot if Google changes their payload. The high-res/portrait half is solid. Worth confirming against a real >30-photo album before we consider google photos screensaver only showing 30 pics in album of approx 8,000 pics #155 fully closed.
• Nit (not blocking): the box blur runs on the main thread per portrait/fit transition (PhotoFrameController.kt:1591) — a per-transition hitch on the Portal CPU; ideally moved to the io executor in a follow-up.

Testing

• ./gradlew :app:compileDebugKotlin + RemoteAlbumTest — green. (The new tests cover the key/token extractors against fixtures; they don't exercise a real Google payload.)

Closes #155. Original work by @miguelsg29 (split out of #164).