Trim comments across Rust and webapp source to direct one-liners (ticket 030)

Pass over src/*.rs, webapp/src/**, and the in-app "?" docs prose:
condensed multi-paragraph doc comments to single lines that state the
non-obvious why, deleted comments that only restated adjacent code, and
tightened the Docs.tsx help-panel wording. No logic, structure, or code
formatting changed — verified via cargo test (143 passed) and
tsc -b && vite build.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XFUNZwCvz3kcod3352ZR2o

webapp/src/components/NavMenu.tsx

@@ -41,18 +41,14 @@ export function NavMenu({ stats }: { stats: Stats | null }) {
     setOpenPanel((current) => (current === name ? null : name))
   }
 
-  // A "?" icon (ticket 021) always opens Docs to that section and flashes it,
-  // even if Docs is already open to a different section — hence forcing
-  // `openPanel` here rather than toggling.
+  // A "?" icon always opens Docs to its section and flashes it, even if Docs is already open elsewhere — hence forcing `openPanel` here rather than toggling.
   useEffect(() => {
     if (!docsNav.target) return
     setOpenPanel('docs')
     setDocsPanelTarget(docsNav.target)
   }, [docsNav.target])
 
-  // Opening Docs the normal way (this button, not a "?" icon) behaves as
-  // before: no forced section, no flash — so any pending help-triggered
-  // target is cleared.
+  // Opening Docs via this button (not a "?" icon) has no forced section or flash, so clear any pending help-triggered target.
   function handleDocsButtonClick() {
     togglePanel('docs')
     setDocsPanelTarget(null)