perf: cut cold-start download 58% and startup heap 22% via measured chunk-graph fixes (#2742)

* fix(ui): update session-switch-resync test to current handleEvent/setSessionTodos signatures

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

* perf(build): split Shiki grammars/themes, CodeMirror legacy modes, and @pierre/diffs into on-demand chunks

Merging @shikijs/langs into one manual vendor chunk made the first language
request download every grammar (7.4 MB raw / 1 MB gzip). Letting Rollup split
these packages per dynamically imported module downloads only the languages,
themes, and modes actually used — matching how the worker build already
behaves. @pierre/diffs is split the same way so its pure patch parser (used by
the eager tool renderer) no longer drags the Shiki-importing render stack into
the startup graph.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

* perf(ui): restore lazy heavy views and stop eager settings-graph loading

- MainLayout: DiffView/FilesView/GitView/PlanView return to lazyWithChunkRecovery
  (they were silently made static in 2031e3b4 while their Suspense wrappers
  remained), keeping the CodeMirror and @pierre/diffs stacks out of startup.
- ContextPanel: same lazy treatment for its Diff/Files/Git/Plan/Walkthrough
  tabs, with null Suspense fallbacks.
- CommandPalette imported getSettingsNavIcon from SettingsView, statically
  pulling the entire settings surface (SkillsPage -> CodeMirrorEditor -> vim
  mode, theme registry -> @pierre/diffs) into the eager graph; the helper now
  lives in lib/settings/metadata.
- The windowed SettingsWindow mounts only after its first open: rendering the
  lazy component closed made React fetch the SettingsView chunk graph at
  startup.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

* perf(ui): keep @pierre/diffs + Shiki out of the eager chat graph and defer diff worker warmup

- DiffWorkerProvider no longer statically imports @pierre/diffs/worker or the
  theme registry, and no longer spawns 3 workers plus a main-thread shared
  highlighter during mount. Pools are created on demand through a dynamic
  module load, warmed via requestIdleCallback after startup settles, and
  useWorkerPool notifies consumers when a pool becomes available.
- ToolPart's rich diff preview moves to lazily loaded ToolPartDiffPreview;
  the plain-text patch (PlainDiffFallback) renders while the chunk loads,
  mirroring the existing error fallback. Theme registration happens during
  render inside the lazy module so PatchDiff never renders unregistered ids.
- ChatInput mounts its lazy ToolOutputDialog only after the first attachment
  preview opens instead of fetching the dialog chunk on the draft screen.
- getMarkdownSyntaxVars moves to a pierre-free markdownSyntaxVars module so
  eager code-rendering consumers stop importing the registration module.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

* perf(web): load ghostty-web and Nerd Fonts on first terminal use

- ghostty-web (638 KB raw JS + WASM VT) is dynamically imported when a
  terminal actually mounts; TerminalView stays eagerly importable for the
  bottom dock.
- The ~2 MB of CDN Nerd Fonts are no longer preloaded and force-loaded on
  every cold start. index.html exposes an idempotent
  __openchamberEnsureNerdFonts hook; TerminalViewport requests it on mount
  and waits up to 2s so a cached font is in place before the glyph atlas is
  built, while a cold CDN fetch never blocks the terminal. Runtimes without
  the hook (VS Code, mobile) resolve immediately, matching their existing
  fallback-font behavior.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

---------

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

packages/ui/src/components/views/SettingsView.tsx

@@ -46,11 +46,11 @@ import { isDesktopLocalOriginActive, isDesktopShell, isVSCodeRuntime, isWebRunti
 import { isWindowsArm64 as isWindowsArm64Platform } from '@/lib/platform';
 import { useI18n } from '@/lib/i18n';
 import { Icon } from "@/components/icon/Icon";
-import type { IconName } from "@/components/icon/icons";
 import { McpIcon } from '@/components/icons/McpIcon';
 import { reloadOpenCodeConfiguration } from '@/stores/useAgentsStore';
 import {
   SETTINGS_PAGE_METADATA,
+  getSettingsNavIcon,
   getSettingsPageMeta,
   resolveSettingsSlug,
   type SettingsPageSlug,
@@ -113,7 +113,6 @@ const pageOrder: SettingsPageSlug[] = [
 
 const NAV_GROUP_ORDER = ['general', 'projects', 'opencode', 'content'] as const;
 
-const SNIPPETS_SETTINGS_ICON = { icon: 'chat-thread' } as const;
 const ADD_PROVIDER_SETTINGS_ID = '__add_provider__';
 
 function buildRuntimeContext(isDesktop: boolean, isMobile: boolean): SettingsRuntimeContext {
@@ -171,65 +170,6 @@ function getCurrentHistoryState(): Record<string, unknown> {
   return window.history.state;
 }
 
-// eslint-disable-next-line react-refresh/only-export-components
-export function getSettingsNavIcon(slug: SettingsPageSlug): IconName | null {
-  switch (slug) {
-    case 'general':
-      return 'settings-3';
-    case 'projects':
-      return 'folders';
-    case 'remote-instances':
-      return 'computer';
-    case 'appearance':
-      return 'palette';
-    case 'chat':
-      return 'chat-ai-3';
-    case 'magic-prompts':
-      return 'ai-generate-2';
-    case 'snippets':
-      return SNIPPETS_SETTINGS_ICON.icon;
-    case 'notifications':
-      return 'notification-3';
-    case 'shortcuts':
-      return 'command';
-    case 'sessions':
-      return 'chat-history';
-
-    case 'providers':
-      return 'cloud';
-    case 'agents':
-      return 'ai-agent';
-    case 'behavior':
-      return 'brain';
-    case 'commands':
-      return 'slash-commands-2';
-    case 'mcp':
-      return null;
-    case 'plugins':
-      return 'plug-2';
-
-    case 'skills.installed':
-      return 'book-open';
-    case 'skills.catalog':
-      return 'book';
-
-    case 'git':
-      return 'git-branch';
-
-    case 'usage':
-      return 'bar-chart-2';
-    case 'voice':
-      return 'mic';
-    case 'tunnel':
-      return 'home-office';
-    case 'about':
-      return 'information';
-    case 'home':
-      return null;
-    default:
-      return 'robot-2';
-  }
-}
 
 export const SettingsView: React.FC<SettingsViewProps> = ({ onClose, forceMobile, isWindowed, visiblePageSlugs, initialMobileStage = 'nav' }) => {
   const { t } = useI18n();