fix(web-read-card): carry the base's required read offset in fixtures and specs

The base's ReadResultView now requires `offset` (persisted so an empty window
still knows its start). The connection fixture's read sample and read-card.spec's
resultRead helper supply it (the window's first line, 41).

packages/client/connection/src/client/fixture.ts

@@ -397,7 +397,7 @@ function presentResult(name: string, argsRaw: string, resultText: string): ToolR
   // so `call.card` alone does not distinguish it from edit/write.
   if (name === 'read') {
     return {
-      card: 'read', path: READ_SAMPLE_PATH, lines: READ_SAMPLE_LINES,
+      card: 'read', path: READ_SAMPLE_PATH, offset: READ_SAMPLE_FIRST_LINE, lines: READ_SAMPLE_LINES,
       totalLines: READ_SAMPLE_TOTAL, lang: 'ts', content: text(resultText),
     }
   }

packages/client/ui-conversation/tests/read-card.spec.tsx

@@ -46,7 +46,7 @@ const sampleLines = [
 
 /** The read tool's own result view for a settled file read. */
 const resultRead = (over?: Partial<Extract<ToolResultView, { card: 'read' }>>): ToolResultView => ({
-  card: 'read', path: 'src/a.ts', lines: sampleLines, totalLines: 180, lang: 'ts', ...over,
+  card: 'read', path: 'src/a.ts', offset: 41, lines: sampleLines, totalLines: 180, lang: 'ts', ...over,
 })
 
 const running = (over?: Partial<RunningToolCall>): RunningToolCall => ({