Revert "fix(projects): route auto-summary through main model"

This reverts commit ec3853a78a.

src/fabledassistant/services/projects.py

@@ -119,17 +119,12 @@ async def generate_project_summary(user_id: int, project_id: int) -> None:
             f"Recent notes:\n{note_snippets}"
         )
 
-        # Project summarization is synthesis over ~10 notes — too hard for the
-        # 3B background model, which produces incoherent, repetitive output
-        # (misspellings, broken parens, cliché filler). Route through the main
-        # chat model instead. These are rare events (only when a project
-        # changes), so the main model's KV cache eviction cost is negligible.
         from fabledassistant.services.llm import generate_completion
         from fabledassistant.config import Config
         from fabledassistant.services.settings import get_setting
         messages = [{"role": "user", "content": prompt}]
-        main_model = await get_setting(user_id, "default_model", Config.OLLAMA_MODEL)
-        summary = await generate_completion(messages, model=main_model, max_tokens=400, num_ctx=2048)
+        bg_model = await get_setting(user_id, "background_model", Config.OLLAMA_BACKGROUND_MODEL)
+        summary = await generate_completion(messages, model=bg_model, max_tokens=400, num_ctx=2048)
         if not summary:
             return