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/HelpIcon.tsx

@@ -1,10 +1,6 @@
 import { useDocsNav } from '../lib/docsNav'
 
-/**
- * A small "?" affordance that opens the Docs panel scrolled to (and
- * flashing) a specific section (ticket 021), instead of the user having to
- * find it themselves in the Docs accordion.
- */
+// Opens the Docs panel scrolled to (and flashing) sectionId, instead of the user hunting for it in the Docs accordion (ticket 021).
 export function HelpIcon({ sectionId, label }: { sectionId: string; label?: string }) {
   const { openSection } = useDocsNav()
   return (