Remove Workspace trial fields and trial extension logic

[BrewingCoder]

Parent: #25 — Remove all SaaS billing code

What to Remove

Workspace struct fields

Field	Line	Type
TrialEndDate	299	*time.Time
EligibleForTrialExtension	302	bool
TrialExtensionEnabled	303	bool

Also in Organization struct

Field	Line
TrialEndDate	241

Also in Project struct

Field	Line
TrialEndDate	392

Callers

Backend

File	Line	Usage
private-graph/graph/resolver.go	503, 529, 530	Field mapping to response
private-graph/graph/schema.resolvers.go	537-538	Set on workspace creation
private-graph/graph/schema.resolvers.go	3823-3826	Trial extension mutation (check eligible, extend 7 days, mark ineligible)
private-graph/graph/schema.resolvers.go	6468	TrialEndDate comparison: .Before(time.Now())
private-graph/graph/generated/generated.go	1740, 1759, 11738, 11871	GraphQL complexity resolvers

Frontend (crosses into UI)

File	Usage
src/frontend/src/pages/Billing/utils/utils.ts:49-53	getTrialEndDateMessage()
src/frontend/src/components/Header/Header.tsx:831	Trial end date banner display

Migration Required

• Add DB migration to drop 3 columns from workspaces, 1 from organizations, 1 from projects

Test Plan

• Remove fields from all 3 structs
• Remove trial extension mutation
• Update frontend: remove trial banner and getTrialEndDateMessage()
• Update GraphQL schema
• Regenerate: make private-gen + yarn codegen
• Add column-drop migrations
• Verify build + tests (backend and frontend)

🤖 Generated with Claude Code

[github-actions]

AI Triage: Remove SaaS trial-related fields and logic from Workspace, Organization, and Project structs across backend and frontend, including GraphQL schema and database migrations.

Labels applied: area:backend, tech-debt, component:database, billing-removal, area:frontend, priority:medium, component:graphql