feat(examples): add webhook-driven SaaS template

[fjalil7]

Summary

Adds a webhook-driven SaaS example that demonstrates Commet subscription checkout, Better Auth customer creation, signed webhook handling, local billing state sync, and an events dashboard.

The example now points at published Commet packages instead of workspace packages so it can be tested like a real integrator app.

What changed

• Added examples/webhooks with pricing, auth, checkout, dashboard, billing, and webhook event views.
• Added signed /api/webhooks/commet handling backed by @commet/node@7.3.0.
• Stores webhook deliveries and synchronized billing state in Postgres via Drizzle.
• Supports subscription activation/reactivation, payment recovery, usage recorded events, and customer state snapshots.
• Adds small @commet/next webhook typing support used by the example branch.

Validation

• pnpm biome check --write
• git diff --check origin/main...HEAD
• pnpm build
• pnpm typecheck
• pnpm --filter webhooks-example build
• pnpm --filter webhooks-example typecheck

Notes

origin/beta does not exist in this repo, so this PR targets main. Manual Chrome QA was not run because it was not requested as part of the PR gate.

[linear-code]

BIL-1332

[vercel]

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Project	Deployment	Actions	Updated (UTC)
quota	Ready	Preview, Comment	Jun 22, 2026 4:28pm

6 Skipped Deployments

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balance-fixed	Skipped		Jun 22, 2026 4:28pm
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fixed	Skipped		Jun 22, 2026 4:28pm
metered	Skipped		Jun 22, 2026 4:28pm
seats	Skipped		Jun 22, 2026 4:28pm

[fjalil7]

Superseded by split PRs:\n\n- #169 for the @commet/next patch changeset\n- #170 for the webhooks example-only branch