feat: add generic paginated scheduled reports

[Calmingstorm]

Summary

• add the versioned paginated_embed_v1 producer contract with bounded generic embeds, structured links, hostile-payload rejection, normalized persisted projections, and reaction-driven redraws
• construct renderer registry and pagination service in wiring, inject pagination directly into the reaction cog, and retain atomic state under the configured scheduler persistence root
• carry report_format consistently through scheduler, native tools, API, WebUI, and tool schemas while preserving plain-text behavior and rollback-tolerant schedule persistence
• pass cron_timezone through schedule create/update API calls in an isolated commit with create/update/readback and invalid-timezone coverage

Validation

• full Python suite: passed (6 environment-dependent skips)
• focused report/scheduling tests: 195 passed on the final implementation
• Ruff: clean
• lint no-new: 0 findings
• type no-new: 0 findings
• coverage gate: 0 regressions on final HEAD
• apply-registry gate: 0 findings
• npm run check: passed; production assets rebuilt and reproducible
• generic report UI contract: 7 assertions passed

Boundaries

• no deployment or release-pipeline execution
• no live schedule mutation
• no domain-specific report semantics in the repository

[Calmingstorm]

LGTM at 3b12138 — merge HELD pending branch soak per Aaron. Re-verification: all three round-1 blockers now bite under the exact mutations that exposed them — (1) bypassing unknown-format validation fails FOUR pins, one per surface (native add/update, API create/update); the provider mechanism is fail-closed twice over (absent provider rejects non-empty formats; provider failure rejects); (2) the legacy byte-identity pin fails on a one-character truncation change under a boundary-length result; (3) the update persistence pin does the full disk round-trip (set → reload → clear → reload) and catches set-then-drop. Clean control 309 passed. Round-1 verified findings stand: contract caps exact, four original mutations biting, explicit wiring with components-before-extensions ordering, zero domain terms in source, zero internal IPs, parse-first ordering, cron_timezone isolated in f1647d4. Independent full battery at this head: suite 9,650 passed / 5 skipped, npm run check exit 0 with byte-current dist, coverage/lint/type/apply-registry clean, diff-check clean, CI 7/7. Next: branch soak on the live install (Aaron-authorized), then merge on his word.