feat(read): add discovery monitoring workspace

[agentfleets]

What changed

• Add literature ratings, sortable/scalable library fields, provider-aware citation details, and secure Google Scholar discovery through SerpAPI.
• Add a dedicated discovery workspace with search history, saved searches, an Updates inbox, grouped Following controls, RSS auto-discovery, and collection-seeded recommendations.
• Add scheduled research and social monitoring for authors, journals, topics, citations, RSS, Bluesky, Mastodon, YouTube, and X, plus trend scoring, evidence drill-down, noise controls, health status, and secure X credentials.

Why

• Make Read useful as an ongoing research-monitoring workspace rather than only a static literature library.
• Let users follow relevant researchers, sources, feeds, social conversations, and collection-derived topics from one coherent surface.

Verification

• Tests pass locally / in CI
• Manual verification: production desktop and Electron builds succeeded; packaged macOS arm64 app was installed, launched, and verified against the generated package.
• Desktop frontend tests: 866 passed.
• Electron tests: 623 passed, 2 skipped.
• Desktop and Electron typechecks passed.
• Desktop design-token lint and git diff --check passed.

Doc / spec updates

• No doc impact
• Updated affected doc(s) and bumped Last verified vs code line
• Created/updated an ADR in docs/decisions/ (architectural decisions only)
• Added an entry to docs/changelog.md (user-visible change)

Term consistency (doc-spec §7)

• No new project-specific term
• Added new term(s) to docs/reference/glossary.md (with Distinguish from: line if collisions exist + entry in §12)
• First-use linked in any new doc prose

Memory / context

• Not applicable
• Added/updated memory entry: <name>.md

Anything else

• X integration uses the official API and stores the bearer token through the existing Vault/keychain abstraction; credentials are sent only in the authorization header and are not forwarded across cross-origin redirects.
• Scheduled polling runs while the desktop app is active.