docs(selfhost): add complete and minimal review config templates

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Context

Self-host operators need copyable config files that show the full review surface without forcing them to reverse-engineer .gittensory.yml.example, docs, env flags, and private-config behavior. The existing example is useful, but it is not yet a complete operator template set with a minimal starter profile and an exhaustive commented profile.

Parent: #1680

Requirements

• Add a complete gittensory.yml template that includes every supported gate:, settings:, review:, and features: option with defaults, comments, and allowed values.
• Add a minimal starter template with the smallest safe config for a self-hosted repo maintainer.
• Make the templates work for both public repo-root config and container-private GITTENSORY_REPO_CONFIG_DIR usage.
• Keep private/unsafe policy examples clearly marked as private-config examples only.
• Cross-check the templates against the parser, docs, and tests so they do not drift.

Deliverables

• Template files committed in a discoverable docs/examples location.
• Docs update linking the templates from self-host configuration docs.
• Parser/schema coverage or snapshot coverage proving the templates parse and round-trip where applicable.
• Notes on how to use the templates for awesome-claude, gittensory, and metagraphed without committing private policy.

Acceptance criteria

• Every template parses successfully in tests.
• The exhaustive template lists all allowed values and current defaults.
• The minimal template is safe by default and does not enable write/autonomy behavior by accident.
• No labels beyond maintainer-only.