fix cache-clean hint: dist name is pymol, not pymol-open-source

uv registers the wheel as pymol==3.1.0, so 'uv cache clean
pymol-open-source' is a no-op and the poisoned pure-python wheel
keeps being reinstalled from cache (Prepared in 537ms = no compile).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

pymol-open-source/build

@@ -47,5 +47,5 @@ pbuild::install() {
     # launcher can exist while the compiled ext is missing (pure-python wheel from a
     # poisoned uv cache); import _cmd directly so a broken build dies here, not at runtime
     "$PREFIX/venv/bin/python" -c "import pymol._cmd" || \
-        std::die 42 "pymol._cmd import failed - ext .so missing; try 'uv cache clean pymol-open-source' and rebuild"
+        std::die 42 "pymol._cmd import failed - ext .so missing; try 'uv cache clean pymol' (dist name is pymol, not pymol-open-source) and rebuild"
 }