overview: one endpoint, live projections and a response cache (m36)

src/app.zig

@@ -817,6 +817,9 @@ fn serve(r: cli.Runner, args: cli.RunArgs) !u8 {
     // Same argument as the live hash: a settings PUT may have installed an
     // owned generation, and this runs after `group.cancel`.
     defer web_state.proxies.deinit(gpa);
+    // The Overview response cache owns its bodies from `gpa`. Same argument
+    // again: no web task can still be reading a slot once the group is cancelled.
+    defer web_state.overview_cache.deinit(gpa);
     if (cfg.web.enabled) web_state = .{
         .gpa = gpa,
         .web = cfg.web,