feat: add UserClient and SubmissionsClient modules for comprehensive SDK coverage (#863) [FaaFyfxR9WAQrL7FcAgEHJvztd8cVMxvjHRS55rw1nwH]

[waterWang]

Summary

Add dedicated UserClient and SubmissionsClient resource modules to the SolFoundry TypeScript SDK, completing the API coverage for bounties, submissions, and users as specified in the T3 bounty requirements.

Changes

New: UserClient (sdk/src/users.ts)

• getProfile() — Get the authenticated user's profile
• updateProfile() — Update display name, wallet, bio, skills
• getActivity() — Paginated activity history
• getContributionStats() — Aggregated contribution statistics
• listNotifications() — Paginated notification list with unread filter
• markNotificationRead() / markAllNotificationsRead() — Read/unread management
• getNotificationPreferences() / updateNotificationPreferences() — Preference management

New: SubmissionsClient (sdk/src/submissions.ts)

• list(bountyId) — List all submissions for a bounty
• get(bountyId, submissionId) — Get a specific submission
• create(bountyId, data) — Submit a solution (PR) to a bounty
• updateStatus(bountyId, submissionId, data) — Approve/reject submissions
• getReview(bountyId, submissionId) — Full AI review details with per-model scores

New types (sdk/src/types.ts)

• UserProfile, UserProfileUpdate — User profile models
• UserActivityEntry, UserActivityResponse — Activity history
• UserContributionStats — Aggregated stats
• UserNotification, UserNotificationResponse, UserNotificationPreferences — Notification system
• ModelReviewResult, SubmissionReviewResponse — AI review details

Updated facade (sdk/src/index.ts)

• SolFoundry.users — Access user operations
• SolFoundry.submissions — Access submission operations
• Full type re-exports for all new types

Testing

• 220 tests pass (12 files) — all existing tests continue to pass
• users.test.ts — 11 tests covering all 10 UserClient methods
• submissions.test.ts — 6 tests covering all 5 SubmissionsClient methods
• index.test.ts — Updated to verify new clients via facade
• Follows existing vitest mocking patterns (`vi.fn()` for HttpClient)

Closes #863

Wallet: FaaFyfxR9WAQrL7FcAgEHJvztd8cVMxvjHRS55rw1nwH