fix(2): cc-ci host — declare /etc/timezone (gitea + Debian-image recipes bind it)

gitea (drone's SCM dep) binds /etc/timezone:ro; NixOS time.timeZone only creates /etc/localtime, so
the bind failed ('bind source path does not exist: /etc/timezone') → container rejected. Declare
environment.etc.timezone=UTC. Enables drone Q4.10's gitea dep.

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

nix/hosts/cc-ci/configuration.nix

@@ -26,6 +26,10 @@
   # that bind fails ("bind source path does not exist: /etc/localtime") and the service is rejected.
   # UTC is the right default for a CI host (deterministic timestamps). ---
   time.timeZone = "UTC";
+  # Some recipes ALSO bind-mount /etc/timezone (e.g. gitea, and Debian-based images), which
+  # `time.timeZone` does NOT create (it only makes the /etc/localtime symlink). Without this the
+  # bind fails ("bind source path does not exist: /etc/timezone") and the container is rejected.
+  environment.etc."timezone".text = "UTC\n";
 
   # --- Tailscale (ACCESS-CRITICAL: do not break, this is the only route in) ---
   # Baseline read the hostname from /etc/ts-hostname at eval time; that is impure