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/mainview/ProjectWizard.svelte

@@ -137,6 +137,10 @@
 
   async function createProject() {
     const cwd = sourceType === 'remote' ? `ssh://${sanitize(remoteUser)}@${sanitize(remoteHost)}:${sanitize(remotePath)}` : (sanitizePath(localPath) || localPath.trim());
+    // Ensure directory exists for local paths
+    if (sourceType !== 'remote' && cwd) {
+      try { await appRpc.request['files.ensureDir']({ path: cwd }); } catch { /* best effort */ }
+    }
     onCreated({ id: `p-${Date.now()}`, name: sanitize(projectName) || 'Untitled', cwd, provider, model: model || undefined, systemPrompt: systemPrompt || undefined, autoStart, groupId: selectedGroupId, useWorktrees: useWorktrees || undefined, shell: shellChoice, icon: projectIcon, color: projectColor, modelConfig: Object.keys(modelConfig).length > 0 ? modelConfig : undefined });
     resetState();
   }