chore(gates): finish the Windows sweep — zero clippy findings workspace-wide

Second layer of platform gaps the mac/linux-only gate history left:
unix-only test imports/helpers now cfg-gated (mermaid, fast-worktree,
hunk-tracker, pager-render link test, three pty_e2e module decls),
clippy-suggested cleanups in Windows-cfg code (file-utils classifier,
tui console-mode restore, shared clipboard arboard-error flow, tools
terminal closure, workspace capability tail), and `cargo update` of h2
(RUSTSEC-2026-0258) and webbrowser (RUSTSEC-2026-0257) so `cargo deny
check advisories` passes again.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KSy9S31pZNWXtRZNVJ1sDf

crates/codegen/kigi-workspace/src/foreign_sessions/capability/mod.rs

@@ -224,11 +224,11 @@ impl ApprovedRoot {
             {
                 return None;
             }
-            return Some(OpenedRegularFile {
+            Some(OpenedRegularFile {
                 file,
                 path: canonical_path,
                 metadata,
-            });
+            })
         }
         #[cfg(not(any(unix, windows)))]
         {