perf: overhaul session loading, caching, and runtime isolation (#2360)

Improve OpenChamber responsiveness under large session workloads while fixing
cache, synchronization, and persistence correctness across runtimes, projects,
directories, and worktrees.

- prioritize selected and visible sessions during bootstrap and defer
  non-critical enrichment work
- reduce redundant message loading, event processing, store publication, and
  hidden sidebar work
- prevent stale session and message requests from overwriting newer
  authoritative state
- preserve existing data when authoritative fetches fail instead of treating
  failures as successful empty responses
- scope session materialization, messages, drafts, queues, todos, pins,
  permissions, folders, tabs, Git state, and pull request data by runtime and
  directory identity
- harden runtime switching, reconnect, cleanup, mutation reconciliation, and
  persisted-state ordering
- preserve live subagent Task linkage when metadata arrives after an older
  message request or while streaming parts are suspended
- coalesce overlapping tail refreshes without losing newer refresh demand
- improve cold-session loading by moving deferrable work out of the critical
  bootstrap path
- isolate URL authentication, mobile credentials, native secrets, and other
  runtime-owned state across endpoint changes
- bound long-lived caches and remove avoidable allocations from event and
  rendering hot paths
- limit virtualization to archive collections where it improves rendering
  without disrupting active sidebar layout
- stabilize session folders, pin ordering, expanded state, and persisted
  sidebar behavior
- open skill files through the same secure editor and outside-workspace grant
  flow used by file navigation, including worktree sessions
- expand regression coverage for stale completions, runtime collisions,
  reconnect behavior, persistence races, authoritative empty results, and
  subagent refresh ordering
- document the updated synchronization, cache ownership, performance, and
  runtime-isolation invariants

packages/ui/src/lib/shiki/appThemeRegistry.test.ts

@@ -0,0 +1,33 @@
+import { describe, expect, test } from 'bun:test';
+
+import { themes } from '@/lib/theme/themes';
+import { getResolvedShikiTheme, getThemeContentSignature } from './appThemeRegistry';
+
+describe('appThemeRegistry', () => {
+  test('invalidates resolved themes when content changes under the same ID', () => {
+    const original = themes[0];
+    const changed = {
+      ...original,
+      colors: {
+        ...original.colors,
+        syntax: {
+          ...original.colors.syntax,
+          base: {
+            ...original.colors.syntax.base,
+            keyword: original.colors.syntax.base.string,
+          },
+        },
+      },
+    };
+
+    expect(getThemeContentSignature(changed)).not.toBe(getThemeContentSignature(original));
+    expect(getResolvedShikiTheme(changed)).not.toBe(getResolvedShikiTheme(original));
+  });
+
+  test('reuses resolved themes for identical content', () => {
+    const original = themes[0];
+    const clone = JSON.parse(JSON.stringify(original));
+
+    expect(getResolvedShikiTheme(clone)).toBe(getResolvedShikiTheme(original));
+  });
+});