fix: align config.yaml structure with Pydantic AppConfig schema

config.yaml nested cheshire_cat and face_detector under the 'services' key,
and llama URLs under 'services.llama'. But AppConfig expects:
- services -> {url, amd_url} (llama endpoints directly)
- cheshire_cat -> top-level key
- face_detector -> top-level key

Because Pydantic silently ignores extra fields, ServicesConfig received
{llama: {...}, cheshire_cat: {...}, face_detector: {...}} and none matched
its 'url'/'amd_url' fields, so ALL service config from YAML was silently
ignored and Pydantic defaults were always used instead.

Flattened services to contain url/amd_url directly, and moved cheshire_cat
and face_detector to top-level keys matching the AppConfig model. Verified
both AppConfig(**yaml_data) and config_manager dot-path traversal work.

config.yaml

@@ -6,16 +6,15 @@
 
 # Service Endpoints
 services:
-  llama:
   url: http://llama-swap:8080
   amd_url: http://llama-swap-amd:8080
 
-  cheshire_cat:
+cheshire_cat:
   url: http://cheshire-cat:80
   timeout_seconds: 120
   enabled: true  # Set to false to disable Cheshire Cat integration
 
-  face_detector:
+face_detector:
   startup_timeout_seconds: 60
 
 # AI Models