[derreisende77]

ARTE crawls no longer discover film entries through the retired OPA catalogue API. Replace the active OPA pipeline with EMAC catalogue discovery and player-v2 HLS resolution.

Fixes #1181.

Changes

• Browse each configured sender's ALL_VIDEOS feeds, follow bounded pagination, and expand collections into episodes.
• Deduplicate programme references and apply the existing history filter before requesting player details. Resolve remaining programmes with at most four virtual-thread workers per sender, using the configured rate limiter.
• Preserve the existing ARTE.DE/FR/EN/ES/IT/PL sender mapping and programme identity namespace. Populate metadata, audio-language information, audio descriptions, and catalogue-language subtitles.
• Keep ARTE's published default HLS URLs; validate additional synthesized version URLs before including them. Leave HLS file sizes unknown instead of issuing size probes.
• Isolate malformed catalogue entries and ordinary socket/call timeouts while propagating actual cancellation and closing transport/worker resources.
• Remove unused OPA tasks, DTOs, parsers, version mapping, and their obsolete tests and fixtures. Most deleted lines are retired JSON fixtures; new tests exercise the active crawler path.
• Add a source-based English design document with operational limits and maintenance guidance.

Uses Java 25 and existing MServer libraries; no dependency changes.

Validation

• Java 25: ./mvnw -q clean test — 493 tests passed, no failures/errors; one opt-in live test skipped.
• ./mvnw -q -Dtest=ArteLiveTest -Darte.live=true test — all six sender checks passed; 18 film entries and their HLS playlists verified.
• Design document rendered with Asciidoctor with warnings treated as failures; source links and whitespace checks passed.

The live checks use one page per feed and resolve the first three discovered programmes per sender. They verify playlist availability, not a complete catalogue crawl or full media downloads. Discovery remains bounded by the configured maximumSubpages for each feed.