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/Alerts.tsx

@@ -24,9 +24,7 @@ const OPS: { value: CompareOp; label: string }[] = [
   { value: 'ne', label: '!=' },
 ]
 
-/// Parses a plain millisecond number or a humantime-style duration like
-/// `30s`/`5m`/`1h` into milliseconds. Mirrors the backend's `window_ms`
-/// field without pulling in a full humantime parser for the webapp.
+/// Parses a plain millisecond number or a humantime-style duration (`30s`/`5m`/`1h`) to mirror the backend's `window_ms` without a full humantime parser here.
 function parseWindowMs(input: string): number | null {
   const trimmed = input.trim()
   if (!trimmed) return null
@@ -119,8 +117,6 @@ function formFromRule(rule: AlertRule): FormState {
   return base
 }
 
-/// Validates the form's condition-specific fields, returning an error
-/// message (or null if valid) plus the built `AlertCondition` when valid.
 function buildCondition(form: FormState): { error: string | null; condition: AlertCondition | null } {
   switch (form.kind) {
     case 'immediate':