Use common dispatch for compiled constants

[PhysicistJohn]

Summary

Replace print_constant's exhaustive dtype switch with dispatch_all_types.
Compile-time capability branches retain the existing bool, byte-integer,
integer, floating, and complex formatting paths for every current dtype.

This removes sixteen net lines from one function.

Testing

• Release CPU-only build with C++20 and warnings as errors
• Exact compiled.cpp Release translation-unit replay with warnings as errors;
  the replay matched the stored 41,120-byte object with a 14,836-byte text
  section
• Baseline/candidate generated-text parity for all 14 current dtypes, including
  the int8 and uint8 numeric formatting paths
• Native compile/JIT suite (24/24 cases, 117/117 assertions)
• Full native C++ suite (247/247 cases, 3,326/3,326 assertions)
• Release object and static library each shrink by 512 bytes; defined global
  object and library symbol-name lists are unchanged, while the now-unused
  std::runtime_error(char const*) import is removed
• Same-file overlap check against experimental [Experiment] ROCm backend #2300: it changes
  compiled_check_contiguity and its call in
  compiled_collapse_contiguous_dims, not print_constant; this change adds
  no new conflict to [Experiment] ROCm backend #2300's existing current-main conflict
• clang-format and git diff --check

[zcbenz]

I think this check is redundant?

[PhysicistJohn]

Thanks — yes, good catch. Given the array dtype invariant, dispatch_all_types covers every current array::dtype() value, so the outer sentinel was redundant. I removed it and reran the 14-dtype text parity, compile/JIT tests (24 cases, 117 assertions), and full C++ suite (247 cases, 3,326 assertions); all pass.