remove the hive dashboard's stats page and the price table behind it

The ST4TS page (/stats.html), GET /api/stats-hive, hive-c0re's hive_stats
rollup and the modelPrices option that only fed its cost estimate are
gone. Each agent's own /stats page and the turn-stats database it reads
are unchanged. Setting modelPrices now fails evaluation with a message
saying so.

hive-c0re/src/lifecycle/host_config.rs

@@ -301,9 +301,9 @@ async fn systemd_daemon_reload() -> Result<()> {
 /// `harness` and `work` are absent too: they hold that agent's own runtime
 /// material (`bash-tasks/`, turn-stats and event sqlite dbs) and its, often
 /// very large, worktrees and build trees, none of which the holder has a stated
-/// reason to read, let alone write. hive-c0re still reads `harness` directly on
-/// the host (`stats::hive_stats`), which needs no bind mount into anyone else's
-/// container.
+/// reason to read, let alone write. hive-c0re itself reaches `harness` directly
+/// on the host (the paused marker), which needs no bind mount into anyone
+/// else's container.
 fn bind_child_agent_dirs(child: &str, binds: &mut Vec<BindMount>) {
     let Ok(child) = hive_types::Ident::parse(child) else {
         tracing::warn!(%child, "skipping child bind: invalid agent name");