Phases 0-1 + Sprint A: module split, CLI layer, org-refresh fix, hygiene

- LICENSE (MIT) + README truth-pass; docs/cli.md CLI contract
- CLI subcommands (src/cli_cmds/) per "TUI for users, CLI for users+AI"
- Hub/detail refactor: keymap dispatch, modal split, action enum, BgMsg bus
- Fix: org repos were never refreshed (owner==username match); refresh now
  parallel — 49 repos in ~11s, surfaced 70 previously invisible PRs
- Fix: 3 date bugs in detail/git.rs (format-local, Local::now, 1y month math)
- Stash indicator + [m] actions, session persistence, gh CLI token fallback
- Legacy UI modules removed; plan/ docs (roadmap, audit, debate, handoff)

src/debug.rs

@@ -1,21 +1,31 @@
+//! Timing debug log shown in the hub's bottom debug panel (`--debug` flag).
+//! Backed by thread-locals rather than a field threaded through every
+//! function, since logging is opt-in and call sites are scattered across
+//! the codebase wherever something worth timing happens.
+
 use std::cell::RefCell;
 use std::time::Instant;
 
 thread_local! {
-    static ENABLED: RefCell<bool>        = RefCell::new(false);
-    static LOG:     RefCell<Vec<String>> = RefCell::new(Vec::new());
-    static T0:      RefCell<Option<Instant>> = RefCell::new(None);
+    static ENABLED: RefCell<bool>        = const { RefCell::new(false) };
+    static LOG:     RefCell<Vec<String>> = const { RefCell::new(Vec::new()) };
+    static T0:      RefCell<Option<Instant>> = const { RefCell::new(None) };
 }
 
+/// Turns on debug logging and starts the elapsed-time clock used to
+/// timestamp subsequent `log` entries.
 pub fn enable() {
     ENABLED.with(|e| *e.borrow_mut() = true);
     T0.with(|t|  *t.borrow_mut() = Some(Instant::now()));
 }
 
+/// Whether debug logging is currently on.
 pub fn is_enabled() -> bool {
     ENABLED.with(|e| *e.borrow())
 }
 
+/// Appends a timestamped entry to the debug log. A no-op when logging isn't
+/// enabled, so call sites don't need to guard every call with `is_enabled()`.
 pub fn log(msg: impl Into<String>) {
     if !is_enabled() { return; }
     let ms = T0.with(|t| t.borrow().map(|i| i.elapsed().as_millis()).unwrap_or(0));