calibre-umcp 0.3.3

Scheduled-news recurrence control

• Adds disable_scheduled_news_mutation for a known Calibre recipe. It uses the GUI-thread RecipeModel.un_schedule_recipe() API, never edits scheduler files or metadata.db directly, and remains guarded by the established mutation policy, Calibre 9.12.0 runtime requirement, UI token, explicit mutation enablement and active-library/generation checks.
• Rejects queued or running Fetch News work, verifies the recipe is still registered but unscheduled, preserves its schedule, customisation and library records, and retains prior schedule and last_downloaded metadata in bridge preferences for a future explicit resume feature.
• Disabled recipes remain visible through list_scheduled_news_readonly with enabled: false, previous_schedule_type and previous_schedule; repeated disable calls are idempotent. No re-enable mutation is included.
• Fixes recognition of valid, childless Calibre recipe XML elements in the live recipe model.

Validation

• 130 unit tests passed (9 expected Calibre-contract skips); compilation and diff checks passed.
• Live deployment verified on Calibre 9.12.0: bridge 0.3.3, schema 2, toolset 8.

Closes #9.