fix(electrobun): wizard fixes — native dialog, models, PathBrowser, ensureDir

- Native dialog: resolve to nearest existing parent dir, detect user cancel
  (exit code 1) vs actual error, add createIfMissing option
- Claude models: fallback to KNOWN_CLAUDE_MODELS (6 models) when API key
  unavailable. Adds Opus 4.6, Sonnet 4.6, Opus 4.5, Sonnet 4, Haiku 4.5,
  Sonnet 3.7. Live API paginated to limit=100.
- PathBrowser: Select button moved to sticky header (always visible).
  Current path shown compact in header with RTL ellipsis.
- files.ensureDir RPC: creates directory recursively before project creation
- files.ensureDir added to RPC schema

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

@@ -163,6 +163,16 @@ export function createFilesHandlers() {
       }
     },
 
+    "files.ensureDir": async ({ path: dirPath }: { path: string }) => {
+      try {
+        const resolved = path.resolve(dirPath.replace(/^~/, process.env.HOME ?? ""));
+        fs.mkdirSync(resolved, { recursive: true });
+        return { ok: true, path: resolved };
+      } catch (err) {
+        return { ok: false, error: err instanceof Error ? err.message : String(err) };
+      }
+    },
+
     "files.write": async ({ path: filePath, content }: { path: string; content: string }) => {
       const guard = guardPath(filePath);
       if (!guard.valid) {

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

@@ -56,16 +56,30 @@ export function createMiscHandlers(deps: MiscDeps) {
 
   return {
     // ── Files: picker + homeDir ─────────────────────────────────────────
-    "files.pickDirectory": async ({ startingFolder }: { startingFolder?: string }) => {
+    "files.pickDirectory": async ({ startingFolder, createIfMissing }: { startingFolder?: string; createIfMissing?: boolean }) => {
       try {
         const { execSync } = await import("child_process");
-        const start = startingFolder?.replace(/^~/, process.env.HOME || "/home") || process.env.HOME || "/home";
+        const fs = await import("fs");
+        const home = process.env.HOME || "/home";
+        let start = (startingFolder || "~/").replace(/^~/, home);
+        // Resolve to nearest existing parent
+        while (start && start !== "/" && !fs.existsSync(start)) {
+          start = start.replace(/\/[^/]+\/?$/, "") || home;
+        }
+        if (!start || !fs.existsSync(start)) start = home;
         const result = execSync(
           `zenity --file-selection --directory --title="Select Project Folder" --filename="${start}/"`,
           { encoding: "utf-8", timeout: 120_000 },
         ).trim();
+        if (result && createIfMissing) {
+          fs.mkdirSync(result, { recursive: true });
+        }
         return { path: result || null };
-      } catch {
+      } catch (err: unknown) {
+        // Exit code 1 = user cancelled — not an error
+        if (err && typeof err === "object" && "status" in err && (err as {status:number}).status === 1) {
+          return { path: null };
+        }
         return { path: null };
       }
     },