Add <fmt/format.h> for fmt 11+ compatibility

[idesign0]

What

fmt 11 (2024) reorganized its headers: fmt::format and the other formatting functions moved out of <fmt/core.h> into <fmt/format.h> (core.h became a lightweight base). Files that include only <fmt/core.h> and call fmt::format(...) fail to compile against fmt 11 / 12 with:

error: no member named 'format' in namespace 'fmt'

Homebrew now ships fmt 12.2.0, so this surfaces on macOS / Apple-clang builds.

Fix

Add #include <fmt/format.h> to the affected file(s):

• core/include/moveit/task_constructor/fmt_p.h
• core/include/moveit/task_constructor/stage_p.h
• visualization/visualization_tools/src/display_solution.cpp

<fmt/format.h> provides fmt::format in every fmt release (it pulls in the base header), so this is backward-compatible — no minimum-fmt bump and no behaviour change on older fmt.

Tested on

• macOS 26 (Apple Silicon / arm64) — GitHub Actions macos-26 runners
• Apple clang 21.0.0 (clang-2100.1.1.101, target arm64-apple-darwin25.5.0), C++17, libc++
• fmt 12.2.0 (Homebrew)
• Built from source in a ROS 2 (Humble / Jazzy / Kilted) workspace, CMake 4.3

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 52.93%. Comparing base (722d7b0) to head (6b87e21).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #756   +/-   ##
=======================================
  Coverage   52.93%   52.93%           
=======================================
  Files         138      138           
  Lines       10651    10651           
  Branches     1129     1129           
=======================================
  Hits         5637     5637           
  Misses       5006     5006           
  Partials        8        8           

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[idesign0]

fyi, @traversaro.