feat: implement analytics schema registry

[onyekachi66]

Closes #822

Description:
This PR introduces a central schema registry for analytics events to prevent dashboards from silently breaking when fields are modified.

Changes:

• New Package analytics-registry: Created a dedicated, standalone package at @quickex/analytics-registry.
• Zod-Based Validation: Defined precise event schemas (like payment_initiated, payment_completed, etc.) using Zod. Each schema explicitly includes a version field.
• Runtime Emit Validation: Refactored the frontend event tracking (app/frontend/src/app/pay/PaymentPageClient.tsx) to validate payloads against the registry on emit. Invalid payloads are rejected and an invalid event counter is incremented.
• CI Safety Checks: Implemented scripts/check-schema.mjs and integrated it into our ci.yml pipeline. This asserts that any changes adding required fields or removing existing fields will fail the CI build unless the corresponding schema's version is incremented.
• Dashboards Exportable Structure: Authored an exportRegistry method that exposes the schemas (along with their property typings and required fields) into a readable JSON object, which can be extracted directly into dashboards or external consumers. A schemas.snapshot.json file is additionally maintained to track historical breaking changes across versions.

Acceptance Criteria Verified:

• Every analytics event has a versioned schema in a central registry.
• Events are validated against their schema before being recorded; invalid events are rejected and counted.
• Adding a required field or removing a field fails CI unless the schema version is incremented.
• The registry is exported in a form dashboards and consumers can read.

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[Cedarich]

Kindly fix the failed workflow