refactor(workspace_manager): merge WorkspaceProfile from models.py into workspace_manager.py

Per the 4-criteria decision rule: WorkspaceProfile fails C1 (only used
by the workspace subsystem), fails C2 (no state machine), fails C3 (no
dedicated test file), borderline C4. MERGE into the existing
src/workspace_manager.py which already has WorkspaceManager.

This commit:
 1. Adds WorkspaceProfile class definition to src/workspace_manager.py
    at the top.
 2. Removes the same class def from src/models.py.
 3. Adds lazy re-export via the existing __getattr__ in src/models.py.
 4. Updates workspace_manager.py imports to no longer import from
    models (the class def is now local).

Verification: VC8 (WorkspaceProfile)
  from src.workspace_manager import WorkspaceProfile  # OK
  from src.models            import WorkspaceProfile  # OK (lazy)
  identity check: True

Tests verified (3/3 PASS):
  tests/test_workspace_manager.py (3 tests)

Side effect: also restored the MCPServerConfig class header that was
inadvertently removed by a too-wide set_file_slice in the previous
Phase 3h edit. Added the missing @dataclass + class MCPServerConfig:
declaration + the fields. The class body (to_dict + from_dict) was
already in models.py; only the header was missing.

src/workspace_manager.py

@@ -1,11 +1,36 @@
 import tomllib
 import tomli_w
 
-from pathlib import Path
-from typing  import Dict, Any, Optional, Union
+from dataclasses import dataclass, field
+from pathlib     import Path
+from typing      import Dict, Any, Optional, Union
 
-from src.models import WorkspaceProfile
-from src        import paths
+from src               import paths
+from src.type_aliases import Metadata
+
+
+@dataclass
+class WorkspaceProfile:
+ name:         str
+ ini_content:  str
+ show_windows: Dict[str, bool]
+ panel_states: Metadata
+
+ def to_dict(self) -> Metadata:
+  return {
+   "ini_content":  self.ini_content,
+   "show_windows": self.show_windows,
+   "panel_states": self.panel_states,
+  }
+
+ @classmethod
+ def from_dict(cls, name: str, data: Metadata) -> "WorkspaceProfile":
+  return cls(
+   name         = name,
+   ini_content  = data.get("ini_content", ""),
+   show_windows = data.get("show_windows", {}),
+   panel_states = data.get("panel_states", {}),
+  )
 
 
 class WorkspaceManager: