refactor: remove Tool Configs and Config Folders

These features are fully superseded by Config Profiles which provide:
- Env vars, file mounts, port overrides, start commands, working dirs
- Git mounts, profile composition, cycle detection
- Default selection, project/tool-type scoping

Changes:
- Delete backend models: ToolConfig, ConfigFolder
- Delete backend APIs: tool_configs.py, config_folders.py
- Delete frontend API clients: tool_configs.ts, config_folders.ts
- Remove Tool Config fetching from start_instance, use ConfigProfile only
- Simplify merge_with_config to accept only profile (no tool_configs)
- Remove configs/folders tabs from Tool Workshop page
- Delete associated integration and unit tests
- Add Alembic migration to drop tool_configs and config_folders tables

Quality gates: backend tests 59 passed, frontend typecheck clean

apps/api/tests/unit/test_manifest_compiler.py

@@ -292,24 +292,41 @@ class TestComputeImageTag:
 
 
 class TestMergeWithConfig:
-    """Tests for merge_with_config."""
+    """Tests for merge_with_config (ConfigProfile only)."""
 
-    def test_applies_tool_config_env(self) -> None:
+    def test_no_profile_returns_manifest_unchanged(self) -> None:
         manifest = {"name": "test"}
-        configs = [
-            {"config_type": "env", "key": "FOO", "value": "bar"},
-        ]
-        result = merge_with_config(manifest, configs)
+        result = merge_with_config(manifest)
+        assert result["name"] == "test"
+        assert result["_extra_env"] == {}
+        assert result["_extra_volumes"] == []
+
+    def test_profile_env_vars(self) -> None:
+        manifest = {"name": "test"}
+        profile = {"environment_variables": {"FOO": "bar"}}
+        result = merge_with_config(manifest, profile)
         assert result["_extra_env"]["FOO"] == "bar"
 
-    def test_applies_port_override(self) -> None:
+    def test_profile_mounts(self) -> None:
+        manifest = {"name": "test"}
+        profile = {"mounts": [{"source": "/host", "target": "/container"}]}
+        result = merge_with_config(manifest, profile)
+        assert len(result["_extra_volumes"]) == 1
+
+    def test_profile_port_override(self) -> None:
         manifest = {"name": "test", "default_port": 8080}
-        configs = [{"port_override": 3000}]
-        result = merge_with_config(manifest, configs)
+        profile = {"hints": {"port_override": 3000}}
+        result = merge_with_config(manifest, profile)
         assert result["default_port"] == 3000
 
-    def test_applies_start_command(self) -> None:
+    def test_profile_start_command(self) -> None:
         manifest = {"name": "test", "runtime": {"command": ["/bin/bash"]}}
-        configs = [{"start_command": "/bin/sh"}]
-        result = merge_with_config(manifest, configs)
+        profile = {"hints": {"start_command": "/bin/sh"}}
+        result = merge_with_config(manifest, profile)
         assert result["runtime"]["command"] == ["/bin/sh"]
+
+    def test_profile_working_directory(self) -> None:
+        manifest = {"name": "test"}
+        profile = {"hints": {"working_directory": "/workspace"}}
+        result = merge_with_config(manifest, profile)
+        assert result["runtime"]["working_dir"] == "/workspace"