feat: integrate AgentRQ task manager plugin

- Clone agentrq/agentrq plugin to plugins/agentrq/
- Update package.json name to 'agentrq'
- Add agentrq plugin to tauri.conf.json resources
- Add AGENTRQ_PACKAGE constant and bundled_agentrq_plugin() discovery
- Add install_agentrq_plugin() function to modlens.rs
- Update README with plugin listing

plugins/agentrq/tsconfig.json

@@ -0,0 +1,20 @@
+{
+  "compilerOptions": {
+    "target": "ES2023",
+    "lib": ["ES2023"],
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
+    "types": ["node"],
+    "strict": true,
+    "exactOptionalPropertyTypes": true,
+    "noUncheckedIndexedAccess": true,
+    "noImplicitOverride": true,
+    "noFallthroughCasesInSwitch": true,
+    "verbatimModuleSyntax": true,
+    "isolatedModules": true,
+    "resolveJsonModule": true,
+    "skipLibCheck": true,
+    "noEmit": true
+  },
+  "include": ["src", "test", "tsdown.config.ts"]
+}