fix(electrobun): wizard creation flow + GitLab probe + shell detection + dropdown flip

- Git probe tries GitHub then GitLab for owner/repo shorthand
- Shows "Found on GitHub/GitLab" with platform indicator
- system.shells RPC detects installed shells (bash/zsh/fish/sh/dash)
- CustomDropdown flip logic uses 200px threshold for flip-up
- Project creation properly persists all wizard fields + adds card

ui-electrobun/src/bun/handlers/git-handlers.ts

@@ -8,6 +8,30 @@ import { execSync, spawn } from "child_process";
 
 export function createGitHandlers() {
   return {
+    "system.shells": async () => {
+      const candidates = [
+        { path: '/bin/bash', name: 'bash' },
+        { path: '/bin/zsh', name: 'zsh' },
+        { path: '/bin/fish', name: 'fish' },
+        { path: '/usr/bin/fish', name: 'fish' },
+        { path: '/bin/sh', name: 'sh' },
+        { path: '/usr/bin/dash', name: 'dash' },
+      ];
+      const seen = new Set<string>();
+      const shells: Array<{ path: string; name: string }> = [];
+      for (const c of candidates) {
+        if (seen.has(c.name)) continue;
+        try {
+          fs.statSync(c.path);
+          shells.push(c);
+          seen.add(c.name);
+        } catch {
+          // not installed
+        }
+      }
+      return { shells };
+    },
+
     "ssh.checkSshfs": async () => {
       try {
         const sshfsPath = execSync("which sshfs", { encoding: "utf8", timeout: 3000 }).trim();