refactor(hive-c0re): group src-root files into submodules

stores/ (sqlite-backed host stores + db helper), stats/, agent_config/,
workers/ — pure git-mv moves; crate-root re-exports keep every
crate::<module> path compiling. flake_check stays at root (synchronous
approval-flow validation, not a background worker)

hive-c0re/src/stores/mod.rs

@@ -0,0 +1,14 @@
+//! Sqlite-backed host-side stores (broker, approval / question /
+//! schedule queues, build logs, audit trail, power intent) plus the
+//! shared connection open/migration helper (`db`). Each submodule is
+//! re-exported at the crate root, so `crate::broker::…` etc. keep
+//! working unchanged.
+
+pub mod approvals;
+pub mod audit_log;
+pub mod broker;
+pub mod build_logs;
+pub mod db;
+pub mod operator_questions;
+pub mod power;
+pub mod scheduled_prompts;