refactor: extract Pydantic schemas into schemas/ subpackages

Extract inline Pydantic models from 9 API routers into dedicated
schema modules under schemas/:

- schemas/tool/tool_type.py — ToolTypeCreate, ToolTypeUpdate, etc.
- schemas/tool/tool_instance.py — CreateInstanceRequest, StartInstanceRequest
- schemas/config/config_profile.py — ConfigProfileCreate, ConfigProfileUpdate,
  ConfigProfileResponse, DefaultProfilesUpdate, ValidateGitUrlRequest, etc.
- schemas/system/health.py — DatabaseHealth, DiskHealth, HealthResponse, etc.
- schemas/user/user.py — UserProfileResponse, UserProfileUpdate
- schemas/user/user_config.py — UserConfigResponse, UserConfigUpdate
- schemas/project/project.py — ProjectCreate, ProjectUpdate, etc.
- schemas/project/ssh_key.py — SSHKeyCreate, SSHKeyResponse, etc.
- schemas/project/git_repository.py — GitRepositoryCreate, etc.

API routers now import from src.schemas.* instead of defining inline.
Net change: -548 lines across 16 files.

Quality gates: py_compile passed, ruff passed on all 18 files.

apps/api/src/schemas/project/__init__.py

@@ -1 +1,41 @@
-"""Project module."""
+"""Project schemas module."""
+
+from src.schemas.project.git_repository import (
+    GitRepositoryCreate,
+    GitRepositoryResponse,
+    UpdateSSHKeyRequest,
+    URLParseRequest,
+    URLParseResponse,
+)
+from src.schemas.project.project import (
+    ProjectCreate,
+    ProjectResponse,
+    ProjectUpdate,
+    SetDefaultSSHKeyRequest,
+)
+from src.schemas.project.ssh_key import (
+    SSHKeyCreate,
+    SSHKeyResponse,
+    SignPayloadRequest,
+    SignatureResponse,
+    VerifySignatureRequest,
+    VerifySignatureResponse,
+)
+
+__all__ = [
+    "GitRepositoryCreate",
+    "GitRepositoryResponse",
+    "ProjectCreate",
+    "ProjectResponse",
+    "ProjectUpdate",
+    "SSHKeyCreate",
+    "SSHKeyResponse",
+    "SetDefaultSSHKeyRequest",
+    "SignPayloadRequest",
+    "SignatureResponse",
+    "URLParseRequest",
+    "URLParseResponse",
+    "UpdateSSHKeyRequest",
+    "VerifySignatureRequest",
+    "VerifySignatureResponse",
+]