feat: add Claude backend with automatic Ollama fallback (Claudification Phase 1)

All agents now prefer Claude API when ANTHROPIC_API_KEY is configured,
with automatic fallback to Ollama when offline or unconfigured. New
src/anthropic/ module provides model selection via get_model() factory.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/core/config.py

@@ -64,7 +64,21 @@ class Config(BaseSettings):
     API_PORT: int = Field(default=8000, description="API port")
     API_PREFIX: str = Field(default="/v1", description="API route prefix")
     
-    # Ollama Configuration
+    # Anthropic Configuration (Claude - preferred backend)
+    ANTHROPIC_API_KEY: str | None = Field(
+        default=None,
+        description="Anthropic API key for Claude access"
+    )
+    ANTHROPIC_MODEL: str = Field(
+        default="claude-sonnet-4-20250514",
+        description="Claude model to use"
+    )
+    PREFER_CLOUD_BACKEND: bool = Field(
+        default=True,
+        description="Prefer Claude over Ollama when available"
+    )
+
+    # Ollama Configuration (local fallback)
     OLLAMA_HOST: HttpUrl = Field(
         default="http://localhost:11434",
         description="Ollama server URL"

src/core/startup.py

@@ -9,6 +9,7 @@ from src.agents.biographer import register_biographer
 from src.agents.housekeeper import register_housekeeper
 from src.agents.librarian import register_librarian
 from src.agents.tatlock_core import TATLOCK_CORE_CAPABILITY, tatlock_core_tools
+from src.anthropic.model_selector import check_claude_health, get_model_info
 from src.core.household_registry import get_household_registry
 from src.core.logging_config import get_logger
 
@@ -81,19 +82,29 @@ def register_household_members():
     )
 
 
-def initialize_application():
+async def initialize_application():
     """
     Initialize the application.
 
     Performs all startup tasks:
-    1. Register household members
-    2. (Future) Initialize connections
-    3. (Future) Load configuration
+    1. Check Claude API health (for backend selection)
+    2. Register household members
+    3. (Future) Initialize connections
 
     This should be called once during application startup.
     """
     logger.info("application_initialization_starting")
 
+    # Check Claude API health for backend selection
+    await check_claude_health()
+    model_info = get_model_info()
+    logger.info(
+        "model_backend_configured",
+        backend=model_info["backend"],
+        model=model_info["model"],
+        claude_available=model_info["claude_available"],
+    )
+
     # Register household members
     register_household_members()