GitHub workflows (#428)

Fixes #348 
Fixes #274 
Fixes #149 

- Connect to existing repos
- Push to other branches on GitHub besides main
- Allows force push (with confirmation) dialog

---------

Co-authored-by: graphite-app[bot] <96075541+graphite-app[bot]@users.noreply.github.com>

src/ipc/ipc_client.ts

@@ -554,6 +554,36 @@ export class IpcClient {
   // --- End GitHub Device Flow ---
 
   // --- GitHub Repo Management ---
+  public async listGithubRepos(): Promise<
+    { name: string; full_name: string; private: boolean }[]
+  > {
+    return this.ipcRenderer.invoke("github:list-repos");
+  }
+
+  public async getGithubRepoBranches(
+    owner: string,
+    repo: string,
+  ): Promise<{ name: string; commit: { sha: string } }[]> {
+    return this.ipcRenderer.invoke("github:get-repo-branches", {
+      owner,
+      repo,
+    });
+  }
+
+  public async connectToExistingGithubRepo(
+    owner: string,
+    repo: string,
+    branch: string,
+    appId: number,
+  ): Promise<void> {
+    await this.ipcRenderer.invoke("github:connect-existing-repo", {
+      owner,
+      repo,
+      branch,
+      appId,
+    });
+  }
+
   public async checkGithubRepoAvailable(
     org: string,
     repo: string,
@@ -568,25 +598,25 @@ export class IpcClient {
     org: string,
     repo: string,
     appId: number,
+    branch?: string,
   ): Promise<void> {
     await this.ipcRenderer.invoke("github:create-repo", {
       org,
       repo,
       appId,
+      branch,
     });
   }
 
   // Sync (push) local repo to GitHub
   public async syncGithubRepo(
     appId: number,
+    force?: boolean,
   ): Promise<{ success: boolean; error?: string }> {
-    try {
-      const result = await this.ipcRenderer.invoke("github:push", { appId });
-      return result as { success: boolean; error?: string };
-    } catch (error) {
-      showError(error);
-      throw error;
-    }
+    return this.ipcRenderer.invoke("github:push", {
+      appId,
+      force,
+    });
   }
 
   public async disconnectGithubRepo(appId: number): Promise<void> {