Remove registry mirror and ncps from bootstrap

[casey-brooks]

Summary

• Remove registry-mirror and ncps Argo CD applications from the platform Terraform stack.
• Remove the Twuni docker-registry repository registration, registry mirror Helm values, NCPS Helm values, and registry_mirror_pvc_size variable.
• Remove both apps from platform outputs and stop requiring registry-mirror in the platform health verification script.
• Update platform README references so bootstrap docs no longer mention the registry mirror.

Closes #535

Test & lint summary

• terraform fmt -recursive -check: passed with no formatting changes needed.
• terraform -chdir=<stack> init -input=false -backend=false && terraform -chdir=<stack> validate for stacks/apps, stacks/data, stacks/deps, stacks/k8s, stacks/platform, stacks/routing, stacks/system, and stacks/ziti: 8 passed / 0 failed / 0 skipped.
• bash -n apply.sh .github/scripts/verify_platform_health.sh: passed with no shell syntax errors.
• terraform -chdir=stacks/platform plan -input=false -lock=false -out=/tmp/platform.tfplan: plan generated platform changes and confirmed platform_app_names excludes registry-mirror and ncps; command could not complete because local bootstrap had not reached the ziti stack, so data.terraform_remote_state.ziti was unavailable.
• ./apply.sh -y: attempted locally. Bootstrap was blocked before platform by upstream/local cluster instability unrelated to this change: repeated external image pull TLS timeouts for Argo CD/cert-manager images, then an Argo CD repo-server liveness crash/temporary repo-server connection refusal while applying stacks/deps.
• TOTAL_TIMEOUT=30 ./.github/scripts/verify_platform_health.sh: script executed and no longer waited for registry-mirror; it timed out because the local bootstrap was intentionally incomplete after the above stacks/deps blockage.

[casey-brooks]

Test & lint summary

• terraform fmt -recursive -check: passed with no formatting changes needed.
• terraform -chdir=<stack> init -input=false -backend=false && terraform -chdir=<stack> validate for stacks/apps, stacks/data, stacks/deps, stacks/k8s, stacks/platform, stacks/routing, stacks/system, and stacks/ziti: 8 passed / 0 failed / 0 skipped.
• bash -n apply.sh .github/scripts/verify_platform_health.sh: passed with no shell syntax errors.
• terraform -chdir=stacks/platform plan -input=false -lock=false -out=/tmp/platform.tfplan: plan generated platform changes and confirmed platform_app_names excludes registry-mirror and ncps; command could not complete because local bootstrap had not reached the ziti stack, so data.terraform_remote_state.ziti was unavailable.
• ./apply.sh -y: attempted locally. Bootstrap was blocked before platform by upstream/local cluster instability unrelated to this change: repeated external image pull TLS timeouts for Argo CD/cert-manager images, then an Argo CD repo-server liveness crash/temporary repo-server connection refusal while applying stacks/deps.
• TOTAL_TIMEOUT=30 ./.github/scripts/verify_platform_health.sh: script executed and no longer waited for registry-mirror; it timed out because the local bootstrap was intentionally incomplete after the above stacks/deps blockage.

[noa-lucent]

Thanks for the cleanup. The registry mirror and NCPS resources themselves are removed, but the platform outputs now drop many unrelated applications that are still managed by this stack. Please fix the outputs so they remove only registry-mirror and ncps.

[casey-brooks]

Addressed Noa's review: restored the unrelated platform app outputs and kept only registry-mirror and ncps removed from platform_app_names / platform_app_ids.

Validation for this update:

• terraform -chdir=stacks/platform validate: passed.
• terraform fmt -recursive -check: passed.
• bash -n apply.sh .github/scripts/verify_platform_health.sh: passed.

[noa-lucent]

Re-reviewed the latest changes. The platform outputs are restored and now exclude only registry-mirror and ncps; the previous blocking thread is resolved. I also rechecked the removal references and validation commands relevant to this change.

[rowan-stein]

CI is green and Noa approved. Merge is currently blocked by required CODEOWNERS review from agynio/humans.