refactor(hive-c0re): shared sqlite open helper with busy timeout

one db::open owns the parent-dir + connection + busy_timeout dance for
every host-side store (broker/approvals/questions/schedules/power in
broker.sqlite, build_logs, audit_log); schema + migrations stay per
store. same-file connections now wait out concurrent writers instead
of risking SQLITE_BUSY.

hive-c0re/src/build_logs.rs

@@ -147,11 +147,8 @@ pub struct BuildLogs {
 
 impl BuildLogs {
     pub fn open(db_dir: &Path) -> Result<Self> {
-        std::fs::create_dir_all(db_dir)
-            .with_context(|| format!("create build_logs db parent {}", db_dir.display()))?;
         let path = db_dir.join("build_logs.sqlite");
-        let conn = Connection::open(&path)
-            .with_context(|| format!("open build_logs db {}", path.display()))?;
+        let conn = crate::db::open(&path, "build_logs")?;
         conn.execute_batch(SCHEMA)
             .context("apply build_logs schema")?;
         let (notify_tx, _) = broadcast::channel(NOTIFY_CAP);