Fix: Use unique /Catch2 prefix for reproducible builds

[arryansh5]

Fixes #3042

Summary

Changes the reproducible build path mapping to use /Catch2 prefix instead of empty string, avoiding conflicts when multiple libraries use reproducible builds.

Changes

• Updated -ffile-prefix-map to use /Catch2/ prefix in CMake/CatchMiscFunctions.cmake
• Added path substitution instructions to extras/gdbinit and extras/lldbinit
• Documented the feature in docs/ci-and-misc.md
• Added release notes

Problem Solved

When both Catch2 and user projects enable CATCH_ENABLE_REPRODUCIBLE_BUILD, debuggers (GDB/LLDB) can only map one empty prefix path at a time, causing conflicts. Using a unique /Catch2/ prefix allows both to coexist.

Users need to add to their debugger config:

set substitute-path /Catch2 /path/to/Catch2

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.18%. Comparing base (de7e863) to head (e24f6b6).

Additional details and impacted files

@@            Coverage Diff             @@
##            devel    #3063      +/-   ##
==========================================
+ Coverage   91.14%   91.18%   +0.03%     
==========================================
  Files         202      202              
  Lines        8831     8831              
==========================================
+ Hits         8049     8052       +3     
+ Misses        782      779       -3     

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