docs: add Google Cloud Replicated quick start

[rajshah4]

Adds a Google Compute Engine quick start for Replicated Embedded Cluster, including networking, DNS/TLS, installation, administrator-managed Vertex AI models, GitHub authentication and end-to-end verification. Adds sidebar navigation and a link from the existing Quick Start.

Validated on release 0.74.0: installer/application preflights, trusted HTTPS, persistent PostgreSQL storage, GitHub login, Vertex Gemini 2.5 Flash inference, sandbox terminal execution and a read-only repository conversation. Documents untested backup/restore, upgrades, multiple nodes and automatic certificate renewal.

Validation: Mintlify broken-link check, navigation JSON, shell syntax and git diff --check passed.

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Project	Status	Preview	Updated
all-hands-ai	🟢 Ready	View Preview	Oct 8, 2026, 12:38 PM

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[enyst]

I'm an AI agent based on Opus 5.5, helping Engel Nyst (@enyst) with project work.

I checked this against the Replicated config in OpenHands/OpenHands-Cloud, which defines the Admin Console fields. The GitHub App helper's default flat layout and its callback/webhook URLs match (create_github_app.py#L115-L141), and the BYOK label is exact.

• Vertex table labels don't match the Admin Console. See the inline comment.
• Agent-Assisted Installation sends readers to an open extensions PR (#458). I'd drop this section until the skill is published.
• Kernel section (L129-147) asks readers to install another kernel and edit GRUB, while also saying there's no evidence that kernel 7.0 fails. The config only says Sysbox needs 6.3+ (config.yaml#L1300). Either state a verified requirement or leave the step out.
• Validation Scope and the evaluation details (image …v20260918, installer v2.19.2+k8s-1.36, "the tested installer printed…") read like a test log and will go out of date. A one-line <Note> saying it was tested with 0.74.0 would be enough.

[enyst]

These are the exact Admin Console labels at 0.74.0 (config.yaml#L389-L438). Matching them will make the fields easier to find:

| LLM Provider | Google |
| Google API Type | Google Cloud Platform (Vertex AI) |
| Google Cloud Project ID | Your Vertex inference project ID |
| Google Cloud Location | Your model's supported location; tested with `us-central1` |
| Google Cloud Service Account JSON file | Upload your service-account JSON file |
| Vertex AI Models | One model ID per line; tested with `gemini-2.5-flash` |

[rajshah4]

Thank you for the careful review. Updated the Admin Console labels, removed the unverified kernel-change procedure, and shortened the validation note while preserving what we tested. We’ve retained the installation skill and linked directly to it, rather than to the update PR.