Refactor config-embedding scripts to read from a values file

Three operational scripts embed configuration (org/group hierarchies, persona rosters, reference-clone URLs) directly in code, so a forker must edit Python/Bash to adapt them:

- `scripts/setup-coder-idp-sync.py` (org/group hierarchy dict)
- `scripts/setup-keycloak-hierarchy.py` (realm/persona dict)
- `scripts/preflight-readiness.sh` (reference repo URL arrays)

**Action**: refactor these to read their inputs from a values file (e.g. `values/env.example.yaml` or a dedicated companion file) so adapting them requires only editing configuration, not code.

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Generated by Coder Agents, on behalf of @ausbru87.

Read scripts/setup-coder-idp-sync.py, scripts/setup-keycloak-hierarchy.py, and scripts/preflight-readiness.sh to inventory their embedded configuration, then inspect values/env.example.yaml if present. Define a shared values-file approach and verify that all three scripts use it so a forker can adapt the hierarchies, personas, and reference URLs without editing code.

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