## What this PR does
Replaces Helm lookup functions with FluxCD valuesFrom mechanism for
passing configuration to HelmReleases. This provides cleaner config
propagation and eliminates the need for force reconcile controllers.
### Changes:
**Platform/Tenant charts:**
- Add Secret `cozystack-values` creation in platform chart (for
tenant-root and system namespaces)
- Add Secret `cozystack-values` creation in tenant chart (for child
namespaces)
**cozystack-api:**
- Add `valuesFrom` references to HelmRelease when creating applications
- Filter keys starting with `_` when returning Application specs
- Validate that user values don't contain `_` prefixed keys
**cozystack-controller:**
- Add validation that HelmRelease contains correct valuesFrom
configuration
- Remove `CozystackConfigReconciler` (no longer needed)
- Remove `TenantHelmReconciler` (no longer needed)
**Helm charts (40+ files):**
- Add helper templates in cozy-lib for `_cluster`/`_namespace` access
- Replace ConfigMap lookups with `.Values._cluster.*`
- Replace Namespace annotation lookups with `.Values._namespace.*`
### Architecture:
```
Secret cozystack-values (in each namespace)
├── _cluster: YAML with data from ConfigMaps (cozystack, cozystack-branding, cozystack-scheduling)
└── _namespace: YAML with namespace service references (etcd, host, ingress, monitoring, seaweedfs)
HelmRelease
└── spec.valuesFrom:
├── Secret/cozystack-values → _namespace → .Values._namespace
└── Secret/cozystack-values → _cluster → .Values._cluster
```
### Release note
```release-note
[platform] Replace Helm lookup functions with FluxCD valuesFrom mechanism for configuration propagation
```
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Helm releases and namespaces now source centralized cluster/namespace
configuration via a new secret (cozystack-values), and many templates
read values from chart-provided _cluster/_namespace entries.
* **Bug Fixes**
* API now rejects application specs containing reserved keys prefixed
with "_" to prevent invalid configurations.
* **Refactor**
* Two background reconciler controllers were removed from startup,
simplifying controller initialization.
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settings.</sub>
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
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