docs: the agent config meta-flake input is the local applied mirror, not forge git+http

config-changes.md § Meta flake, hive-c0re nix comments and the meta.rs/exec.rs
doc comments still described the declared agent-<n> input as a forge-hosted
git+http repo; meta.rs renders git+file://<applied>.

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

@@ -28,9 +28,8 @@ in
   # 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
+  # would hang forever and freeze the daemon during startup. 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";