feat(electrobun): project wizard phases 1-5 (WIP)

- sanitize.ts: input sanitization (trim, control chars, path traversal)
- provider-scanner.ts: detect Claude/Codex/Ollama/Gemini availability
- model-fetcher.ts: live model lists from 4 provider APIs
- ModelConfigPanel.svelte: per-provider config (thinking, effort, sandbox, temperature)
- WizardStep1-3.svelte: split wizard into composable steps
- CustomDropdown/Checkbox/Radio: themed UI components
- provider-handlers.ts: provider.scan + provider.models RPC
- Wire providers into wizard step 3 (live detection + model lists)
- Replace native selects in 5 settings panels with CustomDropdown

ui-electrobun/src/bun/index.ts

@@ -33,6 +33,7 @@ import { createSearchHandlers } from "./handlers/search-handlers.ts";
 import { createPluginHandlers } from "./handlers/plugin-handlers.ts";
 import { createRemoteHandlers } from "./handlers/remote-handlers.ts";
 import { createGitHandlers } from "./handlers/git-handlers.ts";
+import { createProviderHandlers } from "./handlers/provider-handlers.ts";
 
 /** Current app version — sourced from electrobun.config.ts at build time. */
 const APP_VERSION = "0.0.1";
@@ -101,6 +102,7 @@ const searchHandlers = createSearchHandlers(searchDb);
 const pluginHandlers = createPluginHandlers();
 const remoteHandlers = createRemoteHandlers(relayClient, settingsDb);
 const gitHandlers = createGitHandlers();
+const providerHandlers = createProviderHandlers();
 
 // ── RPC definition ─────────────────────────────────────────────────────────
 
@@ -127,6 +129,8 @@ const rpc = BrowserView.defineRPC<PtyRPCSchema>({
       ...remoteHandlers,
       // Git
       ...gitHandlers,
+      // Providers
+      ...providerHandlers,
 
       // Native folder picker dialog via zenity (proper GTK folder chooser)
       "files.pickDirectory": async ({ startingFolder }) => {