Improve renderer crash report diagnostics

[nwparker]

Summary

• Add renderer breadcrumbs for bootstrap start/render, window errors, unhandled rejections, and Chromium JS heap samples.
• Add a typed preload IPC path for renderer breadcrumbs with main-process sanitization.
• Coalesce repetitive agent-state crash breadcrumbs so they do not fill the 30-entry crash report ring.

Crash reports

• https://stablygroup.slack.com/archives/C0B4PDCMPPT/p1779230458935639
• https://stablygroup.slack.com/archives/C0B4PDCMPPT/p1779257765726389
• https://stablygroup.slack.com/archives/C0B4PDCMPPT/p1779269594836999

Validation

• pnpm vitest run --config config/vitest.config.ts src/main/crash-reporting/crash-breadcrumb-store.test.ts src/main/ipc/crash-reporting.test.ts src/renderer/src/lib/crash-diagnostics.test.ts
• pnpm run typecheck:node
• pnpm run typecheck:web
• pnpm lint
• git diff --check