fix(#2560): make hive-core git non-interactive + bound stalled fetches

nix/host-modules/hive-c0re/default.nix

@@ -34,6 +34,15 @@ let
     [credential "http://${config.services.hyperhive.forge.domain}"]
     helper = hive-forge
     username = core
+    [http]
+    # Abort a stalled fetch instead of blocking startup indefinitely. If a
+    # git+http transfer (e.g. `nix flake lock` of the forge-hosted config
+    # inputs) drops below 1 KiB/s for 30s -- forge unreachable / not ready
+    # on cold boot -- git fails fast rather than hanging the whole daemon.
+    # Pairs with GIT_TERMINAL_PROMPT=0 (no credential-prompt hang) and the
+    # migration shellout timeout in migrate.rs.
+    lowSpeedLimit = 1024
+    lowSpeedTime = 30
   '';
 
   # git credential helper for hive-core's authenticated fetches of the

nix/host-modules/hive-c0re/environment.nix

@@ -18,6 +18,15 @@ in
   # the writable StateDirectory.
   HOME = "/var/lib/hyperhive";
   HYPERHIVE_GIT = "${pkgs.git}/bin/git";
+  # Never let git block on an interactive credential prompt. hive-core is a
+  # TTY-less system user, so a prompt (e.g. the forge credential helper
+  # returns nothing because the forge isn't reachable yet on cold boot)
+  # would hang forever — this is what froze the whole daemon during startup
+  # migration's `nix flake lock` of the forge-hosted config inputs. With
+  # this set, git fails fast instead of prompting. Paired with the git http
+  # low-speed abort in `safeDirGitconfig` (bounds a stalled transfer) and
+  # the 120s migration shellout timeout in migrate.rs.
+  GIT_TERMINAL_PROMPT = "0";
   # No HIVE_STATIC_DIR: the gateway static-serves the dashboard dist
   # (see the hive-gateway module); this router is API-only.
   # Path to the base agent frontend dist. hive-c0re's