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/drivers/base.py

@@ -130,7 +130,7 @@ class BaseDeviceDriver(ABC):
         start_y: int,
         end_x: int,
         end_y: int,
-        duration_ms: int = 400,
+        duration_ms: int = 800,
     ) -> bool:
         """Performs a drag/swipe gesture from start to end pixel coordinates."""
         ...
@@ -139,7 +139,7 @@ class BaseDeviceDriver(ABC):
     async def swipe_direction(
         self,
         direction: SwipeDirection | Literal["up", "down", "left", "right"],
-        duration_ms: int = 400,
+        duration_ms: int = 800,
     ) -> bool:
         """Performs standard cardinal scrolling gesture across device viewport."""
         ...
@@ -210,7 +210,7 @@ class BaseDeviceDriver(ABC):
         self,
         start_norm: list[int],
         end_norm: list[int],
-        duration_ms: int = 400,
+        duration_ms: int = 800,
     ) -> bool:
         """Swipes between normalized (0-1000 scale) screen coordinates."""
         width, height = self.screen_size