docs: fix 10 rustdoc link warnings, deny broken/private/redundant intra-doc links, doctests deny(warnings) (3 doctests had unused vars/imports)

src/runtime.rs

@@ -76,7 +76,7 @@
 //!   time (`rq-mutex` / `rq-mpmc` / `rq-striped`). Queue ops require
 //!   preemption disabled (debug-asserted there); when the mutex variant is in
 //!   play it is the innermost lock — nothing else is acquired under it.
-//! - Per-slot `cold` locks ([`RawMutex`], non-poisoning, guard enters
+//! - Per-slot `cold` locks (`RawMutex`, non-poisoning, guard enters
 //!   `NoPreempt`) guard the lifecycle collections. **Leaf rule: never hold
 //!   two cold locks at once** — `finalize_actor`'s link cascade and `link()`
 //!   lock peers one at a time (correctness arguments at the call sites).
@@ -144,13 +144,13 @@ pub const DEFAULT_MAX_ACTORS: usize = 16_384;
 /// use smarm::runtime::Config;
 ///
 /// // Use all available CPUs (default):
-/// let c = Config::default();
+/// let _all = Config::default();
 ///
 /// // Exactly 4 scheduler threads:
-/// let c = Config::exact(4);
+/// let _four = Config::exact(4);
 ///
 /// // Between 2 and 8, clamped to available parallelism:
-/// let c = Config::new(2, 8, None);
+/// let _clamped = Config::new(2, 8, None);
 /// ```
 #[derive(Clone, Debug)]
 pub struct Config {