pi: drop redundant pkgs.ghidra from home.packages

The pyghidra-mcp wrapper bakes in GHIDRA_INSTALL_DIR via makeWrapperArgs
referencing pkgs.ghidra, which makes ghidra a runtime closure dep.
Adding pkgs.ghidra explicitly to home.packages caused buildEnv to merge
*two* ghidra-12.0.4 store paths (one from pyghidra's propagatedBuildInputs,
one from the explicit list) and fail with a path collision on
GPL/DMG/LICENSE.txt.

Drop the explicit add. The agent-driven workflow doesn't need the GUI;
manual exploration via 'nix run nixpkgs#ghidra' is one command away if
ever wanted.

home/progs/pi.nix

@@ -138,7 +138,6 @@ in
   home.packages = [
     inputs.llm-agents.packages.${pkgs.stdenv.hostPlatform.system}.omp
     pyghidra-mcp
-    pkgs.ghidra # GUI Ghidra for occasional manual exploration
   ];
 
   home.file = androidSkillFiles // {