Collapse 26 trivial single-package programs into home/programs/common.nix

Consolidates alacritty, audacity, blender, blockbench, claude-code, fd,
filezilla, fzf, gcc, godot_4, imv, jdk21, jetbrains-toolbox, lazygit,
lua-language-server, mpv, nil, nixpkgs-fmt, nodejs, obsidian, pkg-config,
prismlauncher, vesktop, xclip, xwallpaper, yt-dlp into a single list.

rustup.nix kept separate due to its configuration (session vars, many deps).

Updates imports:
- hivebrain: all 26 + rustup now via common.nix + rustup.nix
- nikita-nixos: blender.nix → common.nix (gets all lightweight tools)

hosts/hivebrain/home.nix

@@ -9,33 +9,8 @@
     ../../home/symlinks.nix
     ../../home/tmux.nix
     ../../home/packages-base.nix
-    ../../home/programs/alacritty.nix
-    ../../home/programs/audacity.nix
-    ../../home/programs/blender.nix
-    ../../home/programs/blockbench.nix
-    ../../home/programs/claude-code.nix
-    ../../home/programs/fd.nix
-    ../../home/programs/filezilla.nix
-    ../../home/programs/fzf.nix
-    ../../home/programs/gcc.nix
-    ../../home/programs/godot.nix
-    ../../home/programs/imv.nix
-    ../../home/programs/jetbrains-toolbox.nix
-    ../../home/programs/jdk.nix
-    ../../home/programs/lazygit.nix
-    ../../home/programs/lua-language-server.nix
-    ../../home/programs/mpv.nix
-    ../../home/programs/nil.nix
-    ../../home/programs/nixpkgs-fmt.nix
-    ../../home/programs/nodejs.nix
-    ../../home/programs/obsidian.nix
-    ../../home/programs/pkg-config.nix
-    ../../home/programs/prismlauncher.nix
+    ../../home/programs/common.nix
     ../../home/programs/rustup.nix
-    ../../home/programs/vesktop.nix
-    ../../home/programs/xclip.nix
-    ../../home/programs/xwallpaper.nix
-    ../../home/programs/yt-dlp.nix
   ];
 
   home.username = "marvin";