fix: unified_search + ai_proactive get API key from DB, fix model names for Ollama Cloud

- query_understanding.py: get API key/base_url/provider_type from ai_providers DB
- embedding.py: get API key from DB, pass db+tenant_id through call chain
- routes.py: pass db+tenant_id to llm_analyze_query and llm_aggregate_results
- search_engine.py: pass db+tenant_id to generate_embedding
- unified_search/jobs.py: pass db+tenant_id to generate_embedding
- Fix all default model names: ollama/deepseek-v4 -> ollama/deepseek-v4-flash
- Ollama Cloud has no embedding endpoint; embedding calls fail gracefully

app/plugins/builtins/ai_proactive/jobs.py

@@ -186,7 +186,7 @@ async def deep_analysis(
             extended_context["similar"] = {}
 
         # Generate extended suggestion with deep analysis prompt
-        model = settings.model or "ollama/deepseek-v4"
+        model = settings.model or "ollama/deepseek-v4-flash"
 
         # Get API key from DB (like ai_assistant does) or fall back to env
         from app.plugins.builtins.ai_proactive.services import _get_llm_api_key
@@ -195,7 +195,7 @@ async def deep_analysis(
             api_key = os.environ.get('API_KEY_OLLAMA_CLOUD', '') or None
 
         # Build model string with provider prefix
-        model = settings.model or "ollama/deepseek-v4"
+        model = settings.model or "ollama/deepseek-v4-flash"
         if provider_type:
             model_parts = model.split("/", 1)
             model = f"{provider_type}/{model_parts[-1]}"