fix: set keep_alive to 2h on all Ollama requests

Prevents models from sitting in VRAM indefinitely. Applies to both
streaming chat calls and the non-streaming generate_completion path,
as well as the startup warm-up request.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/fabledassistant/app.py

@@ -169,7 +169,7 @@ def create_app() -> Quart:
                 async with httpx.AsyncClient(timeout=300.0) as client:
                     await client.post(
                         f"{Config.OLLAMA_URL}/api/generate",
-                        json={"model": model, "prompt": "", "keep_alive": "30m"},
+                        json={"model": model, "prompt": "", "keep_alive": "2h"},
                     )
                 logger.info("Warmed model '%s' into VRAM", model)
             except Exception:

src/fabledassistant/services/llm.py

@@ -122,7 +122,7 @@ async def stream_chat(
     merged_options = {"num_ctx": Config.OLLAMA_NUM_CTX}
     if options:
         merged_options.update(options)
-    payload: dict = {"model": model, "messages": messages, "stream": True, "options": merged_options, "think": think}
+    payload: dict = {"model": model, "messages": messages, "stream": True, "options": merged_options, "think": think, "keep_alive": "2h"}
     # read=None: no per-chunk timeout — Ollama may pause for any duration while
     # processing a large input context before the first token arrives.
     async with httpx.AsyncClient(timeout=httpx.Timeout(connect=30.0, read=None, write=None, pool=30.0)) as client:
@@ -176,6 +176,7 @@ async def stream_chat_with_tools(
         "stream": True,
         "options": options,
         "think": think,
+        "keep_alive": "2h",
     }
     if tools:
         payload["tools"] = tools
@@ -256,6 +257,7 @@ async def generate_completion(
                         "stream": False,
                         "think": False,
                         "options": options,
+                        "keep_alive": "2h",
                     },
                 )
                 resp.raise_for_status()