Read engine configuration live instead of asserting it in the dashboard

The engine subtitles were hardcoded: "FlashAttention + Q4 KV Cache" and "DynamicVRAM
+ Pinned Async Offload". The first turned out to be accurate -- OLLAMA_FLASH_ATTENTION
and OLLAMA_KV_CACHE_TYPE really are set -- which is worse than being wrong, because it
would have gone on looking accurate after the settings changed.

engines.py reads both engines' real configuration: the ollama service environment via
systemd, and ComfyUI's own /system_stats for version, allocator, VRAM mode and argv.
Exposed at GET /api/engines, as an MCP tool, and in the dashboard subtitles with the
full settings list as a tooltip.

The settings worth surfacing are the ones that dictate how this service must behave
and that previously had to be discovered by reading journald: OLLAMA_NUM_PARALLEL=1
is why an unload queues behind a running generation and is reported as deferred
rather than failed, and OLLAMA_MAX_LOADED_MODELS=1 is why every swap evicts the
previous model. Each is reported with that explanation attached.

Writing the tests found a bug in the new code: (system.get("python_version") or
"").split()[0] raises IndexError when ComfyUI omits the field, and the surrounding
except would have swallowed it and reported ComfyUI as entirely offline.

Tests: 192 (was 182).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -111,6 +111,18 @@ only if the card actually needs it.
 * **Honest gain reporting**: gain against the profile's *current* setting is reported separately from the spread across values tried. Conflating them turns a flat result into a headline "+102%".
 * **Safety**: refuses to start while ComfyUI is executing, suspends the arbitrator's automatic profile switching for the duration (otherwise a diffusion benchmark trips `trigger_comfy_priority`, which reapplies the whole profile and overwrites the clock being measured), and restores the original profile in a `finally` block — including on exception or cancellation.
 
+### 🔧 Live Engine Configuration (`engines.py`)
+* `GET /api/engines` reports the **real, current** configuration of both engines and what
+  each setting implies for arbitration — because the settings that dictate this service's
+  behaviour live outside its own codebase.
+* `OLLAMA_NUM_PARALLEL=1` is why a `keep_alive: 0` unload queues behind a running
+  generation and is reported as *deferred* rather than failed. `OLLAMA_MAX_LOADED_MODELS=1`
+  is why every swap evicts the previous model. Working these out originally meant reading
+  journald and the systemd unit by hand.
+* The dashboard's engine subtitles now come from this endpoint. They were previously
+  hardcoded — and happened to be accurate, which is worse than being wrong, since they
+  would have kept looking accurate after the configuration changed.
+
 ### 🩺 Dependency Self-Check (`health.py`)
 * `GET /api/health` verifies **everything this service depends on**: NVML, passwordless
   sudo for `nvidia-smi`, fan control through the headless X server, overclock drift, the
@@ -156,7 +168,7 @@ only if the card actually needs it.
 ## 1a. Tests
 
 ```bash
-/home/drjones/comfy-mcp-venv/bin/python -m pytest tests/ -q     # 182 passed in ~3.7s
+/home/drjones/comfy-mcp-venv/bin/python -m pytest tests/ -q     # 192 passed in ~3.7s
 ```
 
 Hermetic: no GPU, no network, no sleeps. An autouse fixture stubs `overclock_manager._sh`
@@ -264,6 +276,7 @@ The HyperSwap server runs on port `9090` by default. Interactive OpenAPI/Swagger
 | `/api/analytics/models` | `GET` | Recency/frequency model ranking used to prioritise the warm budget. |
 | `/api/history?durable=true` | `GET` | Swap history from the persistent store rather than the in-memory ring. |
 | `/api/db` | `GET` | Store location, row counts and how many hours of history are held. |
+| `/api/engines` | `GET` | Live Ollama and ComfyUI configuration, with what each setting implies for arbitration. |
 | `/api/health` | `GET` | Dependency self-check: NVML, sudo, fan control, drift, store, upstreams — each with impact and remediation. |
 
 ### Governor & Autotune Endpoints