Re-enable cosmetic yamllint rules after normalizing vendored manifests

To get CI green on the initial publish, `.yamllint` disables several cosmetic rules (`indentation`, `colons`, `braces`, `document-start`, `line-length`) that the vendored upstream manifests do not follow. Structural checks (syntax, duplicate keys, empty values, trailing whitespace) remain enabled.

**Action (optional, quality)**: progressively normalize the vendored YAML (consistent indentation, `---` document starts, brace/colon spacing) and re-enable the corresponding rules. `line-length` should stay disabled because some manifests embed machine-generated Grafana dashboard JSON on single long lines.

Context: see the CI setup in `.github/workflows/ci.yml` and `.yamllint`.

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Generated by Coder Agents, on behalf of @ausbru87.

Start with .yamllint and .github/workflows/ci.yml, then inspect the vendored YAML manifests that currently violate the cosmetic rules. Normalize indentation, document starts, and brace/colon spacing where practical, re-enable those rules, keep line-length disabled for generated dashboard JSON, and verify CI remains green.

Written by the indexing model from the issue text.