feat(types): define canonical GuildPass SDK V2 public domain types (closes #488)

[rupesh-kumar-sah]

Description

This PR resolves #488 by establishing the canonical public domain types for GuildPass SDK V2, representing Guilds, Members, Passes, Access Policies, Activity Events, and Stellar accounts.

Changes

1. src/types/domain.ts:
   • Defined Guild interface with Stellar owner account and optional Soroban contractId.
   • Defined Member interface and MemberRole union type ('owner' | 'admin' | 'moderator' | 'member').
   • Defined Pass interface and PassStatus union type ('active' | 'expired' | 'revoked' | 'pending').
   • Defined AccessPolicy and AccessPolicyRule interfaces.
   • Defined ActivityEvent interface and ActivityEventType union type.
   • Defined canonical Network and StellarAccount types.
   • Pure domain models without internal database leaks or frontend-only assumptions.
2. src/types/index.ts:
   • Exported all domain types through the public package entry point.
3. tests/domainTypes.test.ts:
   • Added unit test suite ensuring full runtime conformance and TypeScript compilation of all domain types.

Verification

• pnpm typecheck (tsc --noEmit): Passed with 0 errors
• pnpm build (tsup): Clean ESM and type definitions output
• pnpm test (vitest): 24 test files passed, 685 tests passed, 0 failures

Closes #488