System tweaks, gitea CI, boot limit

- nix: keep-outputs + keep-derivations (preserve devshells across GC)
- zramSwap + fstrim
- systemd-boot configurationLimit = 20
- expand .gitignore (editor/AI/stray dotfiles); track statix.toml
- gitea Actions CI: blocking flake-check eval + informational statix/deadnix/nixfmt

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

hosts/common/features/user.nix

@@ -28,6 +28,9 @@
 
   boot.loader = {
     systemd-boot.enable = true;
+    # Cap boot menu entries so old generations don't accumulate forever
+    # (GC prunes the store; this prunes the boot entries).
+    systemd-boot.configurationLimit = 20;
     efi.canTouchEfiVariables = true;
   };
 

hosts/common/global/default.nix

@@ -32,4 +32,10 @@
   };
 
   services.dbus.packages = with pkgs; [ gcr ];
+
+  # Compressed RAM swap — better behaviour under memory pressure.
+  zramSwap.enable = true;
+
+  # Periodic SSD TRIM.
+  services.fstrim.enable = true;
 }

hosts/common/global/nix.nix

@@ -15,6 +15,10 @@
         "flakes"
       ];
       warn-dirty = false;
+      # Keep devshell build inputs alive across GC/`nh clean` so direnv/devenv
+      # projects don't re-download/rebuild their shells after a cleanup.
+      keep-outputs = true;
+      keep-derivations = true;
     };
     # GC is handled by `nh clean` below (keep-N / keep-since semantics).
     # The two are mutually exclusive — nh asserts if nix.gc.automatic is on.