Parse config.yaml into typed AppConfig dataclass

- ServerConfig, VideoConfig, ModelConfig, DeadBugConfig,
  AudioConfig, LoggingConfig as nested dataclasses
- Consumers use config.server.host, config.model.resolved_path etc.
- env var overrides preserved via _apply_env_overrides()

app/core/lifecycle.py

@@ -1,10 +1,10 @@
 from __future__ import annotations
 
 from app.diagnostics.crash_handler import enable_crash_handler
-from configs.load import LOG_DIR
+from configs.load import config
 
 
 def startup() -> None:
-    enable_crash_handler(LOG_DIR)
+    enable_crash_handler(config.logging.dir_path)
     from app.core.logging import setup_logging
     setup_logging()

app/core/logging.py

@@ -4,16 +4,17 @@ from pathlib import Path
 
 from loguru import logger
 
-from configs.load import LOG_DIR, LOG_RETENTION, LOG_ROTATION
+from configs.load import config
 
 
 def setup_logging() -> None:
-    LOG_DIR.mkdir(parents=True, exist_ok=True)
+    log_dir = config.logging.dir_path
+    log_dir.mkdir(parents=True, exist_ok=True)
 
     logger.add(
-        LOG_DIR / "posefit-server_{time:YYYY-MM-DD}.log",
-        rotation=LOG_ROTATION,
-        retention=LOG_RETENTION,
+        log_dir / "posefit-server_{time:YYYY-MM-DD}.log",
+        rotation=config.logging.rotation,
+        retention=config.logging.retention,
         enqueue=True,
         backtrace=True,
         diagnose=True,