phase: 103_suggestions_session_openers

Phase 103 final verification pass — all green.

**Verified (all 3 tasks already in `complete/`; no code changes needed):**
- `opening_questions` in `app/api/suggestions.py` — forward walk, one opener per chat (first non-blank user msg, A3), reads raw `messages` not `title` (A4), phase-80 order/dedup/cap/seed contracts; `last_questions` name gone from `app/`+`tests/`
- Docs updated: `app/config.py` seed docstring, `.env.example` `BOR_SUGGESTIONS`, `README.md` — "session openers" wording
- Diff scope correct: only the 6 expected files + phase-file moves; `app/rag/suggestions.py` and `frontend/` untouched

**Test / lint / coverage results:**
- `uv run pytest tests/integration/test_suggestions_api.py -v` → 12 passed
- `uv run pytest tests/e2e/test_suggestion_chips.py -v --no-cov` → 8 passed in isolation (opener-only core pin included)
- `test_responsive_polish.py` → 7 passed; `test_chat_persistence.py` → 4 passed (both isolated, no edits)
- `uv run pytest --cov=app --cov-report=term-missing` → 2086 passed, TOTAL 99% (>90%); `app/api/suggestions.py` 100%
- `uv run ruff check .` → clean; `uv run pyright` → 0 errors, 0 warnings

**Completion criteria:** all 7 ✅ (follow-ups-never-surface pin; cap-across-chats pin; seed/dedup/case/partial/A3/401 pins; E2E suites isolated; deflection chips unchanged; full suite + lint; commit + dir move left to harness per executor rules).

**Deviations:** none — no defects found; nothing changed in this pass.
**Next pending phase:** `98_sync_summary_visibility` (numeric order in `todo/`).

app/config.py

@@ -375,9 +375,11 @@ class Settings(BaseSettings):
 
     # Onboarding-chip SEED (phase 80, TODO.md L6): shown ONLY while no
     # saved chat has ever asked a question — after that,
-    # ``GET /api/suggestions`` serves the last 3 questions asked
-    # (deployment-wide, newest first). ``BOR_SUGGESTIONS`` overrides
-    # this seed for a new deployment.
+    # ``GET /api/suggestions`` serves the opening questions of the 3
+    # most recent saved chats (the session openers — a chat's first
+    # user question; follow-ups never chip — phase 103; deployment-
+    # wide, newest first). ``BOR_SUGGESTIONS`` overrides this seed
+    # for a new deployment.
     suggestions: list[str] = [
         "What documents are in the knowledge base?",
         "Which source does each answer come from?",