Resolve Resource Inventory

Read docs/30_CURRICULUM_RESOURCE_POLICY.md, docs/32_RESOURCE_RESOLUTION_SPEC.md, data/resource_sources.json, the source PDFs and subject roadmaps. Use ordinary public-source/browser research only; do not bypass access controls. Build data/resolved/resource-items.json using exact source item IDs/titles/URLs/positions. Map every executable topic_video task deterministically. Fixed Math/Turkish sources may not be substituted. Resolve MEB work only to learned-topic-safe official items. Zero-match or multi-match mappings are blocking errors, never guesses. Validate against contracts/resource-item.schema.json and add fixtures/tests before allowing plan commit.