Redesign search: iTunes US + Spotify fallback, fix retry duplicates, strip BBCode

[bigspawn]

Summary

• Search redesign: iTunes US only (no more 4-country fallback with 12s sleep). On miss, Spotify search → Odesli by URL for cross-platform links. 2-3 HTTP requests instead of 6 + 0s sleep instead of 12s.
• Fix duplicate images on retry: SendReleaseNews now deletes the orphaned image before retry (same as SendNews already did), preventing duplicate photos in Telegram on FloodError.
• Strip BBCode from RSS titles: Removes paired BBCode tags ([bb]...[/bb], [b]...[/b], etc.) from RSS feed titles while preserving music markers like [EP], [Single], [Deluxe Edition].
• Relax iTunes requirement: CheckRequiredPlatforms no longer hard-fails when iTunes is missing — only fails if zero required platforms found.
• Go 1.25: Updated go.mod, Dockerfile, and CI workflow.

Test plan

• go build ./...
• go test ./... — all pass
• Unit tests for new GetLinks flow (5 cases), retry logic (4 cases), stripBBCode (14 cases)
• Production: verify faster search, Spotify fallback via Odesli, no duplicate images