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/main.rs

@@ -856,16 +856,6 @@ fn main() {
 
 // ── Command implementations ─────────────────────────────────────────
 
-fn install_default_file(data_dir: &std::path::Path, name: &str, content: &str) -> Result<(), String> {
-    let path = data_dir.join(name);
-    if !path.exists() {
-        std::fs::write(&path, content)
-            .map_err(|e| format!("write {}: {}", name, e))?;
-        println!("Created {}", path.display());
-    }
-    Ok(())
-}
-
 /// Apply links from a single agent result JSON file.
 /// Returns (links_applied, errors).
 fn apply_agent_file(