feat: add CMake check to verify project version agrees with schema version (#144)

Schema version in `edm4eic.yaml` must equal `100*major + 10*minor +
patch` from `CMakeLists.txt`, but this was neither enforced nor in sync
(850 vs 860 for version 8.6.0).

## Changes

- **Fixed version mismatch**: Updated `schema_version` from 850 to 860
- **CMake check**: Fails configuration if `schema_version ≠
100*VERSION_MAJOR + 10*VERSION_MINOR + VERSION_PATCH`

The check runs at CMake configure time, extracts versions, computes
expected schema version, and fails with clear error messages on
mismatch:

```cmake
# In CMakeLists.txt - runs at configure time
math(EXPR EXPECTED_SCHEMA_VERSION "${VERSION_MAJOR} * 100 + ${VERSION_MINOR} * 10 + ${VERSION_PATCH}")
if(NOT SCHEMA_VERSION EQUAL EXPECTED_SCHEMA_VERSION)
  message(FATAL_ERROR "Schema version mismatch: ...")
endif()
```

This CMake-based validation ensures any build attempt will fail if
versions are out of sync, eliminating the need for a separate CI
workflow.

Patch version changes remain schema-invariant as documented.

<!-- START COPILOT ORIGINAL PROMPT -->



<details>

<summary>Original prompt</summary>

> 
> ----
> 
> *This section details on the original issue you should resolve*
> 
> <issue_title>CI check to verify project version agrees with schema
version</issue_title>
> <issue_description>**Is your feature request related to a problem?
Please describe.**
> Sometimes the project version in CMakeLists.txt is updated without
updating the version number in edm4eic.yml, or the other way round.
> 
> **Describe the solution you'd like**
> A small CI test should verify that the project version and schema
version are always in sync. Possibly this can also be implemented as a
CMake requirement and CMake configuration can fail in case of
disagreement.</issue_description>
> 
> ## Comments on the Issue (you are @copilot in this section)
> 
> <comments>
> </comments>
> 


</details>



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- Fixes #143

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: wdconinc <4656391+wdconinc@users.noreply.github.com>

Author: Copilot

CMakeLists.txt

@@ -11,6 +11,24 @@ SET( ${PROJECT_NAME}_VERSION_MINOR 6 )
 SET( ${PROJECT_NAME}_VERSION_PATCH 0 )
 SET( ${PROJECT_NAME}_VERSION  "${${PROJECT_NAME}_VERSION_MAJOR}.${${PROJECT_NAME}_VERSION_MINOR}.${${PROJECT_NAME}_VERSION_PATCH}" )
 
+# Verify that schema version in edm4eic.yaml matches project version
+# Schema version is defined as 100*major + 10*minor + patch
+file(READ "${CMAKE_CURRENT_SOURCE_DIR}/edm4eic.yaml" EDM4EIC_YAML_CONTENT)
+string(REGEX MATCH "schema_version:[ \t]*([0-9]+)" SCHEMA_VERSION_MATCH "${EDM4EIC_YAML_CONTENT}")
+if(SCHEMA_VERSION_MATCH)
+  set(SCHEMA_VERSION ${CMAKE_MATCH_1})
+  math(EXPR EXPECTED_SCHEMA_VERSION "${${PROJECT_NAME}_VERSION_MAJOR} * 100 + ${${PROJECT_NAME}_VERSION_MINOR} * 10 + ${${PROJECT_NAME}_VERSION_PATCH}")
+  if(NOT SCHEMA_VERSION EQUAL EXPECTED_SCHEMA_VERSION)
+    message(FATAL_ERROR
+      "Schema version mismatch: edm4eic.yaml has schema_version=${SCHEMA_VERSION}, "
+      "but CMakeLists.txt version ${${PROJECT_NAME}_VERSION_MAJOR}.${${PROJECT_NAME}_VERSION_MINOR}.${${PROJECT_NAME}_VERSION_PATCH} "
+      "requires schema_version=${EXPECTED_SCHEMA_VERSION}. "
+      "Please update schema_version in edm4eic.yaml to match the project version.")
+  endif()
+else()
+  message(WARNING "Could not find schema_version in edm4eic.yaml")
+endif()
+
 # C++ standard
 set(CMAKE_CXX_STANDARD_MIN 17)
 set(CMAKE_CXX_STANDARD 17 CACHE STRING "Set the C++ standard to be used")

edm4eic.yaml

@@ -3,7 +3,7 @@
 # Some datatypes based on EDM4hep. EDM4hep license applies to those sections.
 ---
 ## Schema versioning
-## This is required to be an integer, and defined as 100*major+minor.
+## This is required to be an integer, and defined as 100*major+10*minor+patch.
 ## Patch level changes are required to be schema invariant.
 ##
 ## If there are schema version changes that can be evolved, see the podio documentation