[vitofico]

Summary

Adds highlight sync through the configured Quire Server account. The existing manual, library-resume and reader-pause sync paths now exchange quotations, exact locators, colours, book snapshots and deletion tombstones; local edits also enqueue sync. Highlights remain independent of downloaded files.

Account-scoped storage and frozen request credentials keep one account's passages out of another account's requests. Existing unowned highlights join the first successfully authenticated highlight account. OPDS-only passages remain local to their catalog/account. Pending edits survive unavailable or older servers, interrupted requests and concurrent local changes.

Server push/pull endpoints use deterministic conflicts and per-user revision cursors protected against late commits. Shared Python/Kotlin wire fixtures check Unicode text, opaque locator preservation and conflict ordering. Identity-hash versions never decrease.

Storage and compatibility

• Room 10→11 preserves existing annotations and adds ownership plus acknowledgement state.
• Append-only Alembic progress_004 adds user-scoped highlights and revision state for full/sync-only deployments; account export/purge includes them.
• Older servers keep progress sync working while highlights remain pending. Reader layout and selection anchoring are unchanged.
• This PR includes both protocol consumers and their migrations/tests so the sync contract can be reviewed together. No agent API, new runtime SDK or shared identity algorithm change.

Validation

• Full server suite against PostgreSQL: 1,016 passed; Ruff check/format passed.
• Android focused tests: 151 passed across local storage, sync and app highlight/account flows; compile passed.
• Independent full source review: passed, with account isolation, exact acknowledgements, paging/rollback, conflict ordering and migrations verified.
• Full GitHub CI passed on e4d5749: Android debug/release builds, all unit tests, lint, 26 browser regressions, license drift and repository/release-tooling guards; server tests in full/sync-only/AI-only modes; Java/Kotlin and Python CodeQL.
• Pre-commit passed on all 42 changed files. Independent review has no unresolved findings.

Related issues

Refs #143. PR 3 follows #164 and #165.