feat: introduce MCP server, cross-platform runtime, and Showcase UI reorganization

- Showcase UI Reorganization:
  * Move web UI dashboard from root directory into apps/showcase_ui/ for cleaner project structure
  * Add 'artemis ui' CLI command (artemis/interfaces/cli/commands/ui.py) and launcher scripts for the interactive showcase console
- Standalone MCP Server & Notifiers (mcp_server/):
  * Implement dedicated MCP server package with mobile automation tools (device_state, inspect_trace, task_manager, task_runner)
  * Add multi-channel notifiers (AgentAPI, Desktop notifications, Webhooks, File output, and Composite routing)
  * Introduce background task runner and trace store for autonomous mobile execution monitoring
- Cross-Platform Runtime & Toolchain Support:
  * Add artemis/platform/ with OS-specific implementations for Linux, macOS (Darwin), and Windows
  * Add artemis/runtime/supervisor.py for resilient process and agent runtime supervision
  * Add artemis/toolchain/ with dependency resolution and SDK descriptors
  * Add cross-platform launcher scripts (start.sh, start.bat) and installer scripts (scripts/install_deps.*)
- Core Enhancements & Diagnostics:
  * Enhance coordinate normalization, OCR API fallback, and perception pipeline
  * Add credential validation (credentials_validator.py) and system diagnostics
  * Update bilingual documentation (README.md, README_CN.md) and architecture diagrams
- Test Suite Expansion:
  * Add integration tests for cloud gateway, remote ADB, and Artemis login
  * Add unit tests covering core diagnostics, platform detection, toolchain, credentials validator, optional OCR, and MCP tools

artemis/tools/base.py

@@ -57,6 +57,10 @@ class ArtemisTool:
         self.handler = handler
         self.category = category
 
+    def is_available(self, ctx: Any = None) -> bool:
+        """Determines if this tool is currently available and should be exposed to agents."""
+        return True
+
     async def execute(self, driver: BaseDeviceDriver, ctx: Any, **kwargs: Any) -> Any:
         """Executes the tool handler with injected driver and context."""
         # Inspect handler signature to only pass supported arguments
@@ -213,25 +217,32 @@ class ToolRegistry:
         return cls._tools.get(normalized)
 
     @classmethod
-    def list_tools(cls, category: ToolCategory | None = None) -> list[ArtemisTool]:
-        """Lists all registered tools, optionally filtered by category."""
+    def list_tools(
+        cls, category: ToolCategory | None = None, available_only: bool = True
+    ) -> list[ArtemisTool]:
+        """Lists all registered tools, optionally filtered by category and availability."""
+        tools = [t for t in cls._tools.values() if not available_only or t.is_available()]
         if category:
-            return [t for t in cls._tools.values() if t.category == category]
-        return list(cls._tools.values())
+            return [t for t in tools if t.category == category]
+        return list(tools)
 
     @classmethod
-    def get_langchain_tools(cls, ctx: Any, names: list[str] | None = None) -> list[BaseTool]:
+    def get_langchain_tools(
+        cls, ctx: Any, names: list[str] | None = None, available_only: bool = True
+    ) -> list[BaseTool]:
         """Returns LangChain tool wrappers for the requested or all registered tools."""
         tools = (
             [cls._tools[n] for n in names if n in cls._tools]
             if names
             else list(cls._tools.values())
         )
+        if available_only:
+            tools = [t for t in tools if t.is_available(ctx)]
         return [t.to_langchain_tool(ctx) for t in tools]
 
     @classmethod
     def get_genai_declarations(
-        cls, names: list[str] | None = None
+        cls, names: list[str] | None = None, available_only: bool = True
     ) -> list[genai_types.FunctionDeclaration]:
         """Returns Google GenAI function declarations for registered tools."""
         tools = (
@@ -239,6 +250,8 @@ class ToolRegistry:
             if names
             else list(cls._tools.values())
         )
+        if available_only:
+            tools = [t for t in tools if t.is_available()]
         return [t.to_genai_declaration() for t in tools]
 
     @classmethod