feat: add PostHog analytics to frontend

[gugu]

No description provided.

[Copilot]

Pull request overview

This pull request adds PostHog analytics integration to the frontend application. PostHog is an open-source product analytics platform that will enable tracking user behavior and product usage.

Changes:

• Added posthog-js package dependency (version ^1.341.0) and its transitive dependencies
• Initialized PostHog in the main application bootstrap file with API key and host configuration

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 3 comments.

File	Description
frontend/package.json	Added posthog-js dependency to project dependencies
frontend/yarn.lock	Added posthog-js and all its transitive dependencies including OpenTelemetry packages, protobuf, and utility libraries
frontend/src/main.ts	Imported posthog-js and initialized PostHog analytics with API key and configuration

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

The configuration option 'defaults' with value '2025-11-30' appears to be invalid. PostHog's init method does not have a 'defaults' configuration option documented in their API. This may have been intended to be 'person_profiles' or another valid configuration option. Additionally, the date '2025-11-30' is in the past (current date is February 2026), which suggests this may be a placeholder or incorrect value. Please verify the intended configuration option and its correct value.

Suggested change

defaults: '2025-11-30',

[Copilot]

PostHog initialization should be conditional based on environment, similar to how Sentry is initialized only when the saas flag is true (lines 73-85). Currently, PostHog will initialize in all environments including local development, which may not be desired and could lead to test/development data being sent to PostHog.

[Copilot]

The PostHog API key is hardcoded directly in the source code. This is a security concern as the key will be visible in version control history and to anyone with access to the repository. Consider moving this to environment configuration files or a secure configuration service, following the same pattern used for Stripe keys (lines 64-67) or Sentry DSN (line 75).

Suggested change

	posthog.init('phc_VPnWHIMj9UjhRLPr7shATjgL0J4KrWWOHkK3JwZbnkw', {
	api_host: 'https://us.i.posthog.com',
	defaults: '2025-11-30',
	});
	const posthogApiKey = (environment as any).posthogApiKey;
	if (posthogApiKey) {
	posthog.init(posthogApiKey, {
	api_host: 'https://us.i.posthog.com',
	defaults: '2025-11-30',
	});
	}