GitHub Import Feature: Import repositories/projects from GitHub (#1424) (#1454)

## Summary
Adds the ability to import GitHub repositories directly into Dyad from
the home screen, complementing the existing local folder import feature.
- GitHub Import Modal: New modal accessible from home screen via "Import
from Github" button with two Import methods
- Select project from GitHub repositories list
- Clone from any GitHub URL
- Advanced Options: Optional custom install/start commands (defaults to
project's package.json scripts)
- Auto AI_RULES Generation: Automatically generates AI_RULES.md if not
present in imported repo

closes #1424
    
<!-- This is an auto-generated description by cubic. -->
---

## Summary by cubic
Adds a GitHub import flow from the home screen so users can clone repos
via their list or any URL, with optional install/start commands and
automatic AI_RULES.md generation. Addresses Linear #1424 by enabling
seamless project setup from GitHub.

- **New Features**
  - Import modal with two tabs: Your Repositories and From URL.
- Advanced options for install/start commands with validation; defaults
used when both are empty.
- After cloning, navigate to chat and auto-generate AI_RULES.md if
missing.
- New IPC handler github:clone-repo-from-url with token auth support,
plus IpcClient method and preload channel.
- E2E tests cover modal open, auth, import via URL/repo list, and
advanced options.

- **Dependencies**
  - Added @radix-ui/react-tabs for the modal tab UI.

<!-- End of auto-generated description by cubic. -->

package-lock.json

@@ -38,6 +38,7 @@
         "@radix-ui/react-separator": "^1.1.2",
         "@radix-ui/react-slot": "^1.2.2",
         "@radix-ui/react-switch": "^1.2.0",
+        "@radix-ui/react-tabs": "^1.0.4",
         "@radix-ui/react-toggle": "^1.1.3",
         "@radix-ui/react-toggle-group": "^1.1.3",
         "@radix-ui/react-tooltip": "^1.1.8",
@@ -5515,6 +5516,36 @@
         }
       }
     },
+    "node_modules/@radix-ui/react-tabs": {
+      "version": "1.1.13",
+      "resolved": "https://registry.npmjs.org/@radix-ui/react-tabs/-/react-tabs-1.1.13.tgz",
+      "integrity": "sha512-7xdcatg7/U+7+Udyoj2zodtI9H/IIopqo+YOIcZOq1nJwXWBZ9p8xiu5llXlekDbZkca79a/fozEYQXIA4sW6A==",
+      "license": "MIT",
+      "dependencies": {
+        "@radix-ui/primitive": "1.1.3",
+        "@radix-ui/react-context": "1.1.2",
+        "@radix-ui/react-direction": "1.1.1",
+        "@radix-ui/react-id": "1.1.1",
+        "@radix-ui/react-presence": "1.1.5",
+        "@radix-ui/react-primitive": "2.1.3",
+        "@radix-ui/react-roving-focus": "1.1.11",
+        "@radix-ui/react-use-controllable-state": "1.2.2"
+      },
+      "peerDependencies": {
+        "@types/react": "*",
+        "@types/react-dom": "*",
+        "react": "^16.8 || ^17.0 || ^18.0 || ^19.0 || ^19.0.0-rc",
+        "react-dom": "^16.8 || ^17.0 || ^18.0 || ^19.0 || ^19.0.0-rc"
+      },
+      "peerDependenciesMeta": {
+        "@types/react": {
+          "optional": true
+        },
+        "@types/react-dom": {
+          "optional": true
+        }
+      }
+    },
     "node_modules/@radix-ui/react-toggle": {
       "version": "1.1.10",
       "resolved": "https://registry.npmjs.org/@radix-ui/react-toggle/-/react-toggle-1.1.10.tgz",