feat(app): live session update + tool renderer + input_tokens migration

SessionDetail live update:
- Extract session-view-state.mjs: capture scroll position, disclosure
  (open/skill-md-open) state, and visible-UUID anchor before refresh;
  reconcile messages by UUID (in-place update, append tail only); restore
  scroll and disclosure state after DOM patch. findLastMessageAtOrAbove uses
  binary search (O(log n)) instead of linear scan.
- scrollRevision tracks user scrolls during refresh to avoid stale anchors
  overriding manual navigation.
- Throttle onScroll to one rAF per frame.

Tool renderer:
- Extract tool-renderer.js: standalone module for rendering tool call cards
  (Read/Write/Edit diffs, Bash terminal output, search results, JS/TS
  syntax highlighting). Replaces inline rendering in SessionDetail.
- tests/app-tool-renderer.test.mjs covers escaping, highlighting, and
  terminal formatting.

Input tokens semantics migration:
- Claude provider now sums input_tokens + cache_creation_input_tokens +
  cache_read_input_tokens into a single input_tokens value (was previously
  only the raw field, undercounting when cache tokens are present).
- One-time index-wide re-parse triggered when the marker
  __claude_input_tokens_include_cache_v1__ is absent and the DB already
  has token data (self-healing on first build after upgrade).
- App indexer.ts carries the same marker check for the app's build path.

Also:
- PRODUCT.md: product register (users, purpose, brand, design principles,
  accessibility targets).
- README.md: minor wording updates.

Co-Authored-By: Codex (GPT-5) <noreply@openai.com>

packages/core/src/providers/claude.ts

@@ -27,6 +27,24 @@ function cursorToSkip(cursor: Cursor): number {
 }
 
 export const name = 'claude';
+export const CLAUDE_INPUT_TOKEN_SEMANTICS_MARKER = '__claude_input_tokens_include_cache_v1__';
+
+function totalInputTokens(usage: Record<string, unknown>): number | null {
+  const fields = [
+    'input_tokens',
+    'cache_creation_input_tokens',
+    'cache_read_input_tokens',
+  ];
+  let seen = false;
+  let total = 0;
+  for (const field of fields) {
+    const value = usage[field];
+    if (typeof value !== 'number' || !Number.isFinite(value)) continue;
+    seen = true;
+    total += value;
+  }
+  return seen ? total : null;
+}
 
 export function discover(_ctx: DiscoverContext): IndexUnit[] {
   return discoverJsonlFiles().map((f: any) => ({
@@ -92,7 +110,7 @@ export function* parse(unit: IndexUnit, cursor: Cursor): Generator<IndexRecord,
         parent_uuid: obj.parentUuid || null, timestamp: ts, role: msg.role || obj.type,
         text, content_type: contentType, is_meta: (isMeta ? 1 : 0), model: msg.model || null,
         is_sidechain: obj.isSidechain ? 1 : 0, agent_id: aid,
-        input_tokens: usage.input_tokens || null, output_tokens: usage.output_tokens || null,
+        input_tokens: totalInputTokens(usage), output_tokens: usage.output_tokens || null,
         cwd: obj.cwd || null, skill: obj.attributionSkill || null, source: 'claude',
       });
     }