Add Opencode and Ollama modules; update configs

Enable Opencode and Ollama in home modules and import their Nix files.
Disable the deprecated system‑module opencode entries and remove it from
the
core packages list.
Add a new GitHub CLI module and a convenient `upf-gh` alias for flake
updates using a GitHub token.
Update the `stylix` configuration to include Opencode styling.
Refresh several flake.lock entries with newer revisions and hashes.

modules/home/ollama.nix

@@ -0,0 +1,20 @@
+{
+  pkgs,
+  lib,
+  config,
+  profile,
+  ...
+}: {
+  options.ollama.enable = lib.mkEnableOption "Ollama";
+
+  config.services.ollama = lib.mkIf config.ollama.enable {
+    enable = true;
+    package = pkgs.ollama;
+    acceleration =
+      if profile == "nvidia"
+      then "cuda"
+      else if profile == "amd"
+      then "rocm"
+      else null;
+  };
+}