restructure: indigo and zlay as peer just modules
move from flat deploy/ and infra/ directories with zlay-prefixed recipes
to symmetric indigo/ and zlay/ peer directories, each with their own
justfile, deploy configs, and terraform. shared configs (cluster-issuer,
postgres-values, grafana-ingress) go to shared/deploy/.
recipes are now invoked as `just indigo <recipe>` / `just zlay <recipe>`
using just's mod feature (1.36.0+). no helm values or terraform resources
changed — purely a repo organization change.
key fix: use source_directory() instead of justfile_directory() in module
justfiles, since justfile_directory() returns the root in modules.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>