refactor: remove config_source flag from bootstrap settings

Database config is now the only option, no need for feature flag.

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

src/central/bootstrap_config.py

@@ -9,7 +9,7 @@ from functools import lru_cache
 from pathlib import Path
 from typing import Literal
 
-from pydantic import Field, field_validator
+from pydantic import Field
 from pydantic_settings import BaseSettings, SettingsConfigDict
 
 
@@ -33,21 +33,6 @@ class Settings(BaseSettings):
         default="INFO",
         description="Logging level",
     )
-    config_source: Literal["toml", "db"] = Field(
-        default="toml",
-        description="Configuration source: 'toml' for TOML file, 'db' for database",
-    )
-    config_toml_path: Path = Field(
-        default=Path("/etc/central/central.toml"),
-        description="Path to TOML config file (when config_source=toml)",
-    )
-
-    @field_validator("config_source")
-    @classmethod
-    def validate_config_source(cls, v: str) -> str:
-        if v not in ("toml", "db"):
-            raise ValueError(f"config_source must be 'toml' or 'db', got {v!r}")
-        return v
 
 
 @lru_cache