phase: 178_split_thinking_levels

## Phase 178 — final verification pass: 100% green

**Verified (all 5 tasks complete in `complete/178_split_thinking_levels/`):**
- `config.py` rename (`llm_chat_thinking_level` default `low`) + new `llm_summary_thinking_level` (default `""`); two `CATALOG` rows; `.env.example` replaced; no stale old-key references (only intentional negative pins in tests)
- Wire split: `chat_stream()` → chat level, one-shot `chat()` → summary level (absent `extra_body` when empty); per-turn line reads chat level only

**Gates:**
- `uv run pytest -k "config and thinking" -v` → 7 passed (defaults + env overrides both knobs)
- `uv run pytest` (unit + integration) → 4170 tests, exit 0; `--cov=app` → **99%** (>90% ✓)
- `uv run ruff check .` clean; `uv run pyright` clean
- `uv run pytest tests/e2e/test_split_thinking_levels.py -v --no-cov` → 3 passed in isolation
- `test_admin_settings_panel.py` + `test_admin_settings_layout.py` → 17 passed in isolation

**Completion criteria:** all 6 test/doc criteria ✅ (admin GET lists both keys, old key gone — integration + E2E pins); commit + phase-dir move = harness's job.

**Documentation:** README.md — both new env vars correctly documented in the LLM (aipi) table with defaults/wire-mapping/off-rule, defaults match `config.py`, all `.env.example` vars covered: verified consistent, no changes needed. AGENTS.md — all referenced files/commands verified to exist, no phase-178 impact (no UI code change, A4): verified consistent, no changes needed.

**Decisions:** none required — no live changes made (E2E booted its own app subprocess against the existing DB).

**Next pending phase:** none — 178 is the last phase in `todo/`.

app/config.py

@@ -105,14 +105,23 @@ class Settings(BaseSettings):
     #: Served by the same OpenAI-compatible endpoint — no new model
     #: management. Called via ``LLMClient.chat()``.
     llm_summary_model: str = "lite"
-    #: The model's thinking level (phase 172, ``BOR_LLM_THINKING_LEVEL``) —
+    #: The chat turn's thinking level (phase 178,
+    #: ``BOR_LLM_CHAT_THINKING_LEVEL``; the phase-172 knob, renamed) —
     #: pi-style reasoning effort, free-form text exactly like
     #: ``llm_chat_model`` (no allowlist — the endpoint is the source of
-    #: truth). Default ``low``. Rides every chat-completions request to
-    #: aipi as the top-level ``reasoning_effort`` parameter
-    #: (``app/rag/llm.py``); the EMPTY value is the off switch — the
-    #: parameter is not sent at all.
-    llm_thinking_level: str = "low"
+    #: truth). Default ``low``. Rides the streaming chat-completions
+    #: requests to aipi as the top-level ``reasoning_effort`` parameter
+    #: (``app/rag/llm.py`` ``chat_stream``); the EMPTY value is the off
+    #: switch — the parameter is not sent at all.
+    llm_chat_thinking_level: str = "low"
+    #: The one-shot summary thinking level (phase 178,
+    #: ``BOR_LLM_SUMMARY_THINKING_LEVEL``) — rides the one-shot
+    #: ``chat()`` calls (document summaries, folder summaries, KB
+    #: overview, the ``check_models`` probe) as ``reasoning_effort``.
+    #: Default EMPTY = the off switch (phase-172 A2): the parameter is
+    #: not sent at all; the TODO's "none" means absence, never a
+    #: literal "none" string.
+    llm_summary_thinking_level: str = ""
     #: Operator kill-switch for the ``thinking`` SSE events (phase 17,
     #: ``BOR_STREAM_THINKING``; ``0``/``false`` → off). When off, thinking
     #: pieces are still counted for the per-turn log line but never