feat: configurer delta comme pager git

Active delta avec navigate=true et dark=true.
Met à jour merge.conflictstyle en zdiff3.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

programs/git.nix

@@ -23,11 +23,13 @@
       "CLAUDE.local.md"
     ];
 
-    # see https://github.com/dandavison/delta#get-started
-    #delta.enable = true;
-    # TEMPORARY DEACTIVATED due to the error
-    # error[E0282]: type annotations needed for `Box<_>`
-    #  --> /build/delta-0.17.0-vendor.tar.gz/time/src/format_description/parse/mod.rs:83:9
+    delta = {
+      enable = true;
+      options = {
+        navigate = true;
+        dark = true;
+      };
+    };
 
     settings = {
       alias = {
@@ -41,7 +43,7 @@
         name = "Pierre Martin";
       };
 
-      merge.conflictstyle = "diff3";
+      merge.conflictstyle = "zdiff3";
       diff.colorMoved = "default";
 
       merge.tool = "meld";