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/LogPreview.tsx

@@ -2,10 +2,7 @@ import { useEffect, useRef, useState } from 'react'
 import { metricPrimitiveToDisplayString, type LogEntry, type ParamDeclaration } from '../lib/api'
 import { HelpIcon } from './HelpIcon'
 
-/// localStorage key for LogPreview's selected param columns. Namespaced
-/// under `ottyl.` since this is the app's first localStorage usage — kept
-/// distinct enough that future per-viewer preferences elsewhere in the app
-/// won't collide with it.
+// Namespaced under `ottyl.` so future per-viewer preferences elsewhere in the app won't collide with this key.
 const VISIBLE_PARAM_COLUMNS_STORAGE_KEY = 'ottyl.logPreview.visibleParamColumns'
 
 function loadVisibleParamColumns(): string[] {
@@ -23,8 +20,7 @@ function saveVisibleParamColumns(columns: string[]) {
   try {
     localStorage.setItem(VISIBLE_PARAM_COLUMNS_STORAGE_KEY, JSON.stringify(columns))
   } catch {
-    // best-effort — a private browsing mode or full storage just means the
-    // selection won't persist across reloads.
+    // best-effort — private browsing or full storage just means the selection won't persist across reloads
   }
 }
 
@@ -101,9 +97,7 @@ export function LogPreview({ logs, params }: { logs: LogEntry[]; params: ParamDe
     })
   }
 
-  // Only render columns for params that are both selected and still known to
-  // exist, so a stale localStorage entry for a since-removed param doesn't
-  // leave a dangling column.
+  // Filter out stale localStorage entries for since-removed params, so they don't leave a dangling column.
   const columns = visibleParamColumns.filter((name) => paramNames.includes(name))
 
   return (