feat(ebook-search): set up uv cache management and pruning service

systems/jeeves/runners/uv_cache_prune.nix

@@ -0,0 +1,28 @@
+{ pkgs, ... }:
+let
+  vars = import ../vars.nix;
+  runnerUsername = "gitea-runner";
+in
+{
+  systemd = {
+    services.uv-cache-prune = {
+      description = "Prune the shared gitea runner uv cache";
+      environment.UV_CACHE_DIR = vars.uv_cache;
+      serviceConfig = {
+        Type = "oneshot";
+        User = runnerUsername;
+        Group = runnerUsername;
+        ExecStart = "${pkgs.uv}/bin/uv cache prune";
+      };
+    };
+
+    timers.uv-cache-prune = {
+      description = "Monthly prune of the shared gitea runner uv cache";
+      wantedBy = [ "timers.target" ];
+      timerConfig = {
+        OnCalendar = "*-*-01 04:00:00";
+        Persistent = true;
+      };
+    };
+  };
+}