Clean up unused imports, dead code, and compiler warnings

Remove unused StoreView imports, unused store imports, dead
install_default_file, dead make_report_slug, dead fact-mine/
experience-mine spawning loops in daemon. Fix mut warnings.
Zero compiler warnings now.

poc-memory/src/cli/agent.rs

@@ -1,9 +1,7 @@
 // cli/agent.rs — agent subcommand handlers
 
 use crate::store;
-use crate::store::StoreView;
 use crate::agents::llm;
-use std::sync::atomic::{AtomicUsize, Ordering};
 
 pub fn cmd_run_agent(agent: &str, count: usize, target: &[String], dry_run: bool, debug: bool) -> Result<(), String> {
     if dry_run {