feat: add VS Code extension entry point with model selection

- Register commands for generating commit messages, aborting
  generation, and selecting AI models
- Implement `selectModel` command with progress notification while
  fetching available models from the configured provider
- Display current model in QuickPick and persist selection globally
- Show appropriate error/warning messages on failure or empty results

src/extension.ts

@@ -0,0 +1,52 @@
+import * as vscode from "vscode"
+import { abortGeneration, generateCommitMsg } from "./commitGenerator"
+import { fetchAvailableModels } from "./providers"
+
+export function activate(context: vscode.ExtensionContext): void {
+  context.subscriptions.push(
+    vscode.commands.registerCommand("aiCommit.generateCommitMessage", (scm?: vscode.SourceControl) =>
+      generateCommitMsg(scm),
+    ),
+    vscode.commands.registerCommand("aiCommit.abortGeneration", () => abortGeneration()),
+    vscode.commands.registerCommand("aiCommit.selectModel", () => selectModel()),
+  )
+}
+
+async function selectModel(): Promise<void> {
+  const config = vscode.workspace.getConfiguration("aiCommit")
+
+  let models: string[]
+  try {
+    models = await vscode.window.withProgress(
+      { location: vscode.ProgressLocation.Notification, title: "Zemit: Fetching available models…", cancellable: false },
+      () => fetchAvailableModels(config),
+    )
+  } catch (err) {
+    const msg = err instanceof Error ? err.message : String(err)
+    vscode.window.showErrorMessage(`[Zemit] ${msg}`)
+    return
+  }
+
+  if (models.length === 0) {
+    vscode.window.showWarningMessage("[Zemit] No models found for the configured provider.")
+    return
+  }
+
+  const currentModel = config.get<string>("model", "")
+  const items = models.map((id) => ({
+    label: id,
+    description: id === currentModel ? "current" : undefined,
+  }))
+
+  const picked = await vscode.window.showQuickPick(items, {
+    placeHolder: "Select a model",
+    matchOnDescription: false,
+  })
+
+  if (!picked) return
+
+  await config.update("model", picked.label, vscode.ConfigurationTarget.Global)
+  vscode.window.showInformationMessage(`[Zemit] Model set to ${picked.label}`)
+}
+
+export function deactivate(): void {}