fix: Add publisher to member offerings and extract profile routes (#796)

[bokelley]

Summary

• Fixes Member profile "Publisher" offering option causes validation error (agenticadvertising platform) #796: Backend rejecting "Publisher" as an offering despite frontend showing it as an option
• Creates centralized VALID_* constants for runtime validation to prevent type/runtime drift
• Extracts member profile routes from http.ts to routes/member-profiles.ts (~530 lines removed)
• Adds 'trialing' to subscription status types for trial user support

Changes

• server/src/types.ts: Add VALID_MEMBER_OFFERINGS, VALID_ORGANIZATION_ROLES, VALID_ASSIGNABLE_ROLES, VALID_LEGAL_DOCUMENT_TYPES constants with isValidMemberOffering() type guard
• server/src/db/organization-db.ts: Add VALID_REVENUE_TIERS constant, add 'trialing' to SubscriptionInfo.status
• server/src/billing/stripe-client.ts: Add 'trialing' to subscription status return type
• server/src/routes/member-profiles.ts: New file with extracted member profile routes
• server/src/http.ts: Mount new routers, remove old routes (~530 lines)
• server/src/routes/organizations.ts, billing-public.ts, admin/prospects.ts: Use centralized constants

Test plan

• All 241 tests pass
• TypeScript builds successfully
• Code review completed and suggestions addressed

🤖 Generated with Claude Code