docs(feeds, integration): feed template context traps, CSV full source path, MCP sub-task and grouped-log gaps (5.8.10)

[Justinvolved]

Folds the measured feed and Data Integration traps (DW 10.29.6, MCP 0.6.0-BETA) that the skills did not yet carry. Root-only feed queries, the <repository>.<index> task value and the Excel full-path rule were already present.

• Feed Template provider: the Context:LanguageID macro in a feed query resolves the default language while option names render in the feed language; a NULL Double custom field arrives as 0; the context currency reads USD for a EUR feed. Take each from the product data (catalog-publishing.md §2.7).
• Data Integration: the full-path "Source file" rule is generalised from Excel to the CSV provider, which reads nothing with the folder/file split. get_integration_activity_logs answers "No run log found" for an activity inside a group; read the DataIntegration log file instead (dw-integration-framework Rules).
• Scheduler: get_scheduled_tasks lists only the parent level; scheduler-rows-and-runs.md reads the whole tree from ScheduledTask (dynamo:false skill only).

Version 5.8.10. validate-skills.py exits 0 and build-manifest.mjs --check is clean.