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

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

testing/fake-llm-server/package.json

@@ -21,6 +21,7 @@
     "@types/cors": "^2.8.18",
     "@types/express": "^4.17.21",
     "@types/node": "^20.17.46",
+    "git-http-mock-server": "^2.0.0",
     "ts-node": "^10.9.2",
     "typescript": "^5.8.3"
   }