refactor: extract pydantic schemas from routers into schemas/ directory (Task 3.2)

- Create schemas/ directory with 12 schema files covering all domains
- Extract 70+ Pydantic models from 11 router files
- Routers now import from src.schemas.{domain} instead of defining inline
- Zero inline BaseModel definitions remain in any router

Quality gates: py_compile all schemas (pass), py_compile all routers (pass)
Refs: repo-restructure Task 3.2

apps/api/src/schemas/health.py

@@ -0,0 +1,50 @@
+"""Health check response schemas."""
+
+from pydantic import BaseModel, Field
+
+
+class DatabaseHealth(BaseModel):
+    """Database health check result."""
+
+    status: str = Field(description="Database health status", examples=["healthy"])
+    response_time_ms: float = Field(
+        description="Query response time in milliseconds", examples=[5.2]
+    )
+
+
+class DiskHealth(BaseModel):
+    """Disk space health check result."""
+
+    status: str = Field(description="Disk health status", examples=["healthy"])
+    free_gb: float = Field(description="Free disk space in GB", examples=[45.2])
+    total_gb: float = Field(description="Total disk space in GB", examples=[100.0])
+
+
+class HealthChecks(BaseModel):
+    """Individual health checks."""
+
+    database: DatabaseHealth | None = None
+    disk: DiskHealth | None = None
+
+
+class HealthResponse(BaseModel):
+    """Overall health check response."""
+
+    status: str = Field(description="Overall health status", examples=["healthy"])
+    timestamp: str = Field(
+        description="ISO 8601 timestamp", examples=["2026-05-19T12:00:00Z"]
+    )
+    version: str = Field(description="API version", examples=["0.1.0"])
+    checks: HealthChecks = Field(description="Individual health checks")
+    uptime_seconds: float = Field(
+        description="Server uptime in seconds", examples=[3600.0]
+    )
+
+
+class DatabaseHealthResponse(BaseModel):
+    """Database-specific health check response."""
+
+    status: str = Field(description="Database health status", examples=["healthy"])
+    response_time_ms: float = Field(
+        description="Query response time in milliseconds", examples=[5.2]
+    )

apps/api/src/schemas/user.py

@@ -0,0 +1,19 @@
+"""User request/response schemas."""
+
+import uuid
+
+from pydantic import BaseModel, ConfigDict
+
+
+class UserProfileResponse(BaseModel):
+    model_config = ConfigDict(from_attributes=True)
+
+    id: uuid.UUID
+    email: str
+    name: str
+    avatar_url: str | None
+
+
+class UserProfileUpdate(BaseModel):
+    name: str | None = None
+    email: str | None = None

apps/api/src/schemas/user_config.py

@@ -0,0 +1,21 @@
+"""User config request/response schemas."""
+
+from pydantic import BaseModel, ConfigDict
+
+
+class UserConfigResponse(BaseModel):
+    model_config = ConfigDict(from_attributes=True)
+
+    default_editor: str | None = None
+    theme: str = "system"
+    git_user_name: str | None = None
+    git_user_email: str | None = None
+    last_session_id: str | None = None
+
+
+class UserConfigUpdate(BaseModel):
+    default_editor: str | None = None
+    theme: str | None = None
+    git_user_name: str | None = None
+    git_user_email: str | None = None
+    last_session_id: str | None = None