Slice 8: v1 ships — integration coverage, runbook, spec corrections

- Five new integration test files raise the suite from 75 to 96 green:
  test_hygiene_vertical (7), test_branch_path_routing (4),
  test_metadata_pr_merge (3), test_cache_bootstrap (4), test_e2e_smoke
  (3). The smoke test walks propose → super-draft → edit branch →
  body-edit PR → graduate → active-RFC PR → merge → notification →
  hygiene-sweep deletion end-to-end.
- deploy/RUNBOOK.md replaces the prior DEPLOY.md stub as a real
  runbook: prerequisites, first-time bring-up, day-2 ops (logs, DB
  backup, secret rotation, the §12 hygiene cadence), rollback shape,
  troubleshooting table.
- backend/.env.example grows the SMTP block, HYGIENE_TICK_SECONDS,
  and WEBHOOK_EMAIL_BOUNCE_SECRET with inline commentary.
- README points to RUNBOOK.md; the "what the build lets you do"
  section adds Slices 7 and 8.
- docs/DEV.md gets a Slice 8 — shipped section; the "Next slice"
  footer becomes the v1-complete epitaph.
- SPEC corrections per the §19.3 working agreement: §10.7 names the
  shared §12 sweep; §12 names the bot as actuator and the per-user
  branch_chat_seen preservation contract; §19.1 marks v1 complete
  and records Slice 8; the five §19.2 candidates Slice 8 folded in
  are marked settled with pointers at the resolution.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/.env.example

@@ -41,3 +41,43 @@ ENABLED_MODELS=claude
 ANTHROPIC_API_KEY=
 GOOGLE_API_KEY=
 OPENAI_API_KEY=
+
+# --- Email (§15.4) ---
+# Leave SMTP_HOST unset to use the stdout fallback — the integration
+# tests rely on it, and a dev environment without a real SMTP provider
+# still sees envelope traces in the logs. Set the rest to wire a real
+# provider (Postmark, Mailgun, SES, etc.).
+SMTP_HOST=
+SMTP_PORT=587
+SMTP_USER=
+SMTP_PASSWORD=
+SMTP_STARTTLS=1
+
+# Single non-spoofing envelope identity per §15.9 — every notification
+# email goes out from the same address regardless of which user's
+# gesture produced it. Configure both the SPF and DKIM records for
+# this address with the chosen SMTP provider.
+EMAIL_FROM=notifications@wiggleverse.local
+EMAIL_FROM_NAME=Wiggleverse
+
+# §15.4 bundle threshold: when a user's quiet-hours release queue is
+# at least this big, the flush goes out as one bundled "Activity while
+# you were away" email instead of individual sends.
+EMAIL_BUNDLE_THRESHOLD=5
+
+# Set to 0 to suppress every outbound email (the inbox and SSE still
+# work — only the email channel turns off).
+EMAIL_ENABLED=1
+
+# --- Email-bounce webhook (§15.4 + §19.2-settled) ---
+# When set, `/api/webhooks/email-bounce` requires the same value in
+# the `X-Webhook-Secret` header. Pick a long random string and
+# configure the SMTP provider's webhook to inject it. When unset,
+# the webhook stays unauthenticated for dev — the v1 contract.
+WEBHOOK_EMAIL_BOUNCE_SECRET=
+
+# --- §12 hygiene cadence (Slice 8) ---
+# How often the hygiene scheduler sweeps for the 30/90-day boundaries.
+# Production default is hourly; tests override to seconds via the same
+# env var.
+HYGIENE_TICK_SECONDS=3600