feat(latex): add watch command

latex/flake.nix

@@ -11,6 +11,13 @@
         pkgs = import nixpkgs {
           inherit system;
         };
+
+        watchLatex = pkgs.writeShellApplication {
+          name = "watch-latex";
+          text = ''
+            latexmk -pdf -pdflatex='pdflatex -interaction=nonstopmode' -pvc -view=none
+          '';
+        };
       in {
         devShells.default = pkgs.mkShell {
           packages = with pkgs; [ 
@@ -21,6 +28,8 @@
             gnumake
             latexminted
 
+            watchLatex
+
             # Presentation tools
             pdfpc
             pympress