Document updated Linux Agent setup

[cursor]

Summary

• Updated Linux installation docs with verified automated installer modes, service options, custom controller support, pool-name quoting, and client-only behavior when INSTALL_JUICE_POOL is omitted.
• Expanded Docker Agent docs with current official image usage, required environment variables, UDP networking guidance, and custom build inputs.
• Updated Kubernetes Agent docs with corrected secret name, chart values, DaemonSet example, GPU node selection, and pod IP networking constraints.
• Refined Linux requirements and troubleshooting for glibc, client vs Agent dependencies, Docker port publishing, and Kubernetes pod-network reachability.

Source coverage

• Verified against accessible recent merged source changes in Juice-Labs/juice-oss: installer PRs for glibc floor, optional pool/client-only installs, custom controller support, service command changes, and pool-name quoting; Docker Agent rebuild/startup changes; Helm chart values/templates.
• Direct gh access to Juice-Labs/juice returned a repository resolution error in this automation environment, so source behavior was verified from the accessible open source mirror used by existing docs links.

Knowledge gaps addressed

• Clarified when the Linux installer creates an Agent service versus only installing client binaries.
• Documented installer flags that affect service startup, release selection, custom controller hosts, and preserved JUICE_* environment variables.
• Added concrete Docker Compose/CLI examples and the required network address/port constraints.
• Added Kubernetes chart defaults and networking caveats that were previously only discoverable from chart templates.

Validation

• npm run build succeeds after npm ci.
• Existing site-wide edit-link warnings and stale Browserslist data still appear during build.