fix(rust): resolve all clippy warnings treated as errors in CI

Fix 18 clippy errors across 7 files:
- lib.rs: change doc comment to regular comment (empty line after doc)
- arch_audit.rs: replace format!() with string literal, use is_none_or
- code_quality.rs: collapsible if, map_or → is_none_or
- commit.rs: collapsible match guard
- explore.rs: needless_range_loop → iterator enumerate
- skills.rs: map_or(false,...) → is_some_and
- semantic_search.rs: map_or → is_none_or, sort_by → sort_by_key,
  remove explicit type to avoid type_complexity

CI was failing with 'error: could not compile zesdex-infrastructure
due to 18 previous errors' at clippy step.

apps/infrastructure/src/lib.rs

@@ -54,8 +54,8 @@ pub use zesdex_domain::*;
 use std::path::PathBuf;
 use std::sync::Arc;
 
-/// Which kind of caller (main agent vs. subagent vs. reviewer) is
-/// invoking a tool, used to scope permissions and tag log/output paths.
+// Which kind of caller (main agent vs. subagent vs. reviewer) is
+// invoking a tool, used to scope permissions and tag log/output paths.
 // ---------------------------------------------------------------------------
 // TurnEvent & runtime types have been moved to zesdex_domain::agent
 // ---------------------------------------------------------------------------