feat: persist goals and reading activity with derived progress

[Eoic]

Summary

Replace example goal/session responses with owned persisted goals and an immutable reading-activity ledger. Calendar-aware projections support books, reading time, pages, and reading days, with overlapping interval/coverage deduplication and retained rule/period history.

Tracking capability version 2 adds book_ids for goals scoped to multiple selected books. Validate every selected book's ownership for definitions and period snapshots, reject impossible books-finished targets, and preserve existing single-book payloads. Shared Dart/Python fixtures cover multi-book projection and eligible time after creation cutoffs and overlapping logs.

Validation

• Latest focused tracking service, goal route, and sync route run: 27 passed.
• Ruff lint/format checks and strict Mypy passed.
• Earlier migration tests preserve existing book data; the latest changes extend the JSON tracking payload and require no additional migration.
• Live multi-device PowerSync transport remains unverified.

Compatibility and delivery

Apply additive Alembic revision b5c6d7e8f901, publication/grants, and PowerSync streams before releasing the integrated client. Advertise tracking_schema_version: 2; existing metric strings remain, with additive reading_days. Older clients can continue using single-book/library goals, while newer clients stage unsupported multi-book tracking on older servers.

Versions remain unchanged; target development. Coordinate client #40, reader #5, and workspace #13. Current Goals UI screenshots are embedded in the client PR.

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-06T14:30:08.261091Z	91a1612	PR opened

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Reviewed commit: 91a1612a0c

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