feat: add memory system activity display

Implements issue #118 to display auto-memory system operations and
provide a browser for viewing memory files.

Backend changes:
- Detect memory file operations in format_tool_description()
- Add emoji icons (📝/💾) for memory Read/Write/Edit operations
- Add list_memory_files() Tauri command to find all memory files
- Add 4 new tests for memory detection logic
- Update Tauri capabilities to allow reading .claude directory

Frontend changes:
- Create MemoryBrowserPanel component with file list and viewer
- Add memory panel to main app layout
- Support Markdown rendering of memory file contents
- Add loading states and error handling

Testing:
- All 354 Rust tests passing
- TypeScript type-checks pass

Co-Authored-By: Hikari <hikari@nhcarrigan.com>

src-tauri/capabilities/default.json

@@ -28,6 +28,18 @@
       "identifier": "fs:allow-write-file",
       "allow": [{ "path": "**" }]
     },
+    {
+      "identifier": "fs:scope",
+      "allow": [
+        { "path": "$HOME/.claude/**" }
+      ]
+    },
+    {
+      "identifier": "fs:allow-read-text-file",
+      "allow": [
+        { "path": "$HOME/.claude/**" }
+      ]
+    },
     "core:window:allow-set-size",
     "core:window:allow-set-always-on-top",
     "core:window:allow-inner-size",