Feat/v0.5 upcoming rail-v2

[apantaz]

Summary

• Add broad backfill and intelligent incremental TMDB enrichment modes
• Prioritize upcoming, recent, Top 10, incomplete, and popular titles
• Deduplicate enrichment across regions and providers
• Add configurable freshness windows and per-run limits
• Support metadata-only execution, dry runs, and exported plans
• Persist completed batches for resumable enrichment
• Add pipeline observability and request accounting
• Add the observed TV Romance genre mapping
• Document the enrichment workflow and configuration

Validation

• 115 Python tests passed
• Ruff linting and formatting passed
• dbt compile, docs generation, and parse passed
• Secret detection passed
• Pre-push coverage suite passed

No TMDB enrichment was executed.