refactor: remove cron pipeline, usage reports, and wiki promote lifecycle

[yw0nam]

Summary

• Remove the cron pipeline (scripts/cron/, CronRun model/table, cron-run tracking/export, kb-submit-cron-run), the usage/daily reports (OpenCode/Hermes/Claude-Code report CLIs + the MetricsRecord/metrics table + upsert_metrics), and the wiki promote/review lifecycle (pages.review_status column, promote/approve/reject/ttl_sweep service fns + MCP tools, the rejected/ export tree, the wiki-approval/usage-report-setup/cron-wrapup/memory-report skills, and the review-console specs PRODUCT.md/DESIGN.md).
• Add Alembic migration a1b2c3d4e5f6 dropping the review_status column and the cron_runs/metrics tables (with a working downgrade), prune the tests that targeted removed features, and scrub the docs/skills of the removed surfaces. MCP write tools go 12 → 6.

Component(s) touched

• scripts/ (ingest-github.sh / kb_update.sh / lint.sh)
• src/kb/ (CLI tools)
• .claude/skills/ (skill files)
• frontend/ (Vite + React SPA)
• test/
• .github/ (CI / templates)
• CLAUDE.md / docs
• Data pipeline behavior (Ingest → Graph → Fill → Lint → Log)

Test plan

• uv run pytest — all green (97 passed; the drop from the 121 baseline is exactly the removed-feature tests)
• uv run kb-lint-wiki — N/A (no wiki-corpus change); ./scripts/lint.sh (ruff + black on src/) is clean instead
• Manual smoke:
  • alembic upgrade head → single head a1b2c3d4e5f6; downgrade -1 → upgrade head round-trip passes (test_alembic_round_trip)
  • live DB confirms cron_runs / metrics / pages.review_status are gone
  • kb-mcp registers exactly 6 write tools (create_raw_source, upsert_page, patch_page, create_handoff, create_operation_log, export_markdown); get_schema no longer lists cron_runs/metrics

Notes for reviewer

• Migration is reversible: downgrade() recreates the column + both tables (nullable review_status matching c11f4e8a92db; the original inline CHECK is intentionally omitted per plan — it only affects the rollback path of a deleted feature).
• Kept surface unchanged: raw ingest, wiki page create/update/patch, handoffs, operation logs, Markdown export, kb-lint, kb-mcp reads (query_sql/get_schema), and the wiki-authoring/wiki-note/handoff-document/knowledgebase-initialize skills. The two bundled summary templates were genericized (usage-report metrics + promote language stripped) rather than deleted, since summary stays a first-class wiki type.
• Out of repo (manual follow-up for the operator): remove the live crontab entries and the ~/.hermes/scripts/kb-*.sh proxy files on the host — these are not tracked here.
• Unrelated in-progress working-tree changes (an export_path data/ strip fix in handoffs.py/pages.py) were deliberately excluded from this branch.