Make claw's REPL feel self-explanatory from analysis through commit

Claw already had the core slash-command and git primitives, but the UX
still made users work to discover them, understand current workspace
state, and trust what `/commit` was about to do. This change tightens
that flow in the same places Codex-style CLIs do: command discovery,
live status, typo recovery, and commit preflight/output.

The REPL banner and `/help` now surface a clearer starter path, unknown
slash commands suggest likely matches, `/status` includes actionable git
state, and `/commit` explains what it is staging and committing before
and after the model writes the Lore message. I also cleared the
workspace's existing clippy blockers so the verification lane can stay
fully green.

Constraint: Improve UX inside the existing Rust CLI surfaces without adding new dependencies
Rejected: Add more slash commands first | discoverability and feedback were the bigger friction points
Rejected: Split verification lint fixes into a second commit | user requested one solid commit
Confidence: high
Scope-risk: moderate
Directive: Keep slash discoverability, status reporting, and commit reporting aligned so `/help`, `/status`, and `/commit` tell the same workflow story
Tested: cargo fmt --all; cargo clippy --workspace --all-targets -- -D warnings; cargo test --workspace
Not-tested: Manual interactive REPL session against live Anthropic/xAI endpoints

rust/crates/api/tests/provider_client_integration.rs

@@ -57,7 +57,7 @@ fn env_lock() -> std::sync::MutexGuard<'static, ()> {
     static LOCK: OnceLock<Mutex<()>> = OnceLock::new();
     LOCK.get_or_init(|| Mutex::new(()))
         .lock()
-        .unwrap_or_else(|poisoned| poisoned.into_inner())
+        .unwrap_or_else(std::sync::PoisonError::into_inner)
 }
 
 struct EnvVarGuard {