feat: migrate to ep_plugin_helpers padToggle for User + Pad Wide settings

[JohnMcLear]

Summary

• Migrate the hand-rolled "Show Comments" User Settings checkbox to ep_plugin_helpers padToggle so the same toggle now appears in both the User Settings panel and the Pad Wide Settings panel — matching how native Etherpad toggles (sticky chat, line numbers, etc.) work.
• Pad-wide value rides Etherpad's existing padoptions COLLABROOM rail (broadcast to every connected client, persisted, honored by enforceSettings).
• The helper owns checkbox rendering, cookie persistence, broadcast sync, enforce, and i18n. The hand-rolled templates/settings.ejs, manual click wiring, and direct padcookie plumbing are gone.

Compatibility

• Depends on ep_plugin_helpers ^0.3.0 (already published to npm).
• Pad Wide Settings column lights up once etherpad-lite feat(padOptions): pass plugin-namespaced ep_* keys through applyPadSettings etherpad#7698 lands; until then, capability detection makes the pad-wide block a no-op and the plugin renders only User Settings — same UX as today, no regression.

Changes

• index.js — register padToggle server hooks (loadSettings, eejsBlock_mySettings, eejsBlock_padSettings); merge helper's clientVars into existing clientVars so displayCommentAsIcon / highlightSelectedText and the helper's ep_plugin_helpers.padToggle.ep_comments_page block both ship to the client.
• static/js/index.js — replace the padcookie.getPref('comments') + manual #options-comments change handler with commentsToggle.init({onChange: applyVisibility}). Re-export handleClientMessage_CLIENT_MESSAGE so the helper refreshes when another user toggles the pad-wide checkbox.
• ep.json — register loadSettings, eejsBlock_padSettings, and client_hooks.handleClientMessage_CLIENT_MESSAGE.
• package.json — add "ep_plugin_helpers": "^0.3.0" dep, bump 11.0.30 → 11.1.0.
• templates/settings.ejs — deleted (only contained the migrated <input>+<label>).

Sub-path imports used per the helper's docs: server ep_plugin_helpers/pad-toggle-server, client ep_plugin_helpers/pad-toggle. Importing the top-level ep_plugin_helpers from client code drags settings/toggle (which reach eejs/Settings) into the esbuild bundle and breaks it.

Test plan

• CI backend tests pass (l10n.js, padCopy.js, padRemove.js, readOnlyPad.js, relative_time.js).
• CI frontend tests pass.
• On a patched Etherpad core (>= 2.7.4): both checkboxes render, toggling User Settings persists per-user via cookie, toggling Pad Wide Settings broadcasts to all clients and is honored by enforceSettings.
• On an un-patched core: only User Settings renders; cookie toggle behaves identically to before this PR.
• Comments pane shows/hides via the resolved effective value on initial load.

🤖 Generated with Claude Code

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