fea(ci): add example charts sync validation

[paul-unifra]

Add Chart Sync Validation

1. Added a GitHub Action that triggers on:

• Changes to chart production values files
• Changes to example production values files
• Changes to Chart.yaml files
• Changes to examples/Makefile.example

2. Added a validation script that performs two main checks:

• Ensures production values files in charts/*/values/ have matching copies in examples/values/
• Validates that versions in examples/Makefile.example match their corresponding chart versions

The script provides detailed diff output when files are out of sync, making it easy to spot differences.

Example Output

When files are out of sync:

❌ Files are not in sync!
Source file: charts/service/values/production.yaml
Target file: examples/values/service-production.yaml
--------------------------------------------------------------------------------
--- Source
+++ Target
@@ -1,5 +1,6 @@
 config:
-  key: old_value
+  key: new_value
+  new_key: value

When versions don't match:

❌ Version mismatch in Makefile.example for service
  Makefile version: 0.0.1
  Chart version: 0.0.2

Purpose

This validation helps ensure that:

1. Example files stay up to date with their source files
2. Chart versions in the example Makefile match the actual chart versions
3. Contributors don't accidentally forget to update example files