[PB-045] Add reproducible Supabase storage bucket provisioning for project documents

[Bdon101]

Task ID

PB-045

Owner Role

agent1

Depends On

• PB-030

Context

Document upload code expects a storage bucket (default project-documents), but fresh environments do not provision this bucket from repo-owned setup. Upload behavior can fail in new setups unless bucket creation is done manually.

Goal

Make storage bucket setup reproducible from repository migrations/setup so document upload works in fresh environments without manual Supabase dashboard steps.

Acceptance Criteria

• Repo-managed setup creates/verifies the required document bucket (project-documents by default).
• Bucket config matches upload constraints (private bucket, 15MB limit, allowed mime types used by upload validator).
• Environment docs clearly describe bucket name overrides and required settings.
• Fresh environment initialized from repo setup can upload a supported file through /api/projects/:projectId/documents.
• Failure mode for missing/misconfigured bucket returns actionable error text.

Constraints

• Keep current upload API surface and storage key pattern unchanged.
• Do not expose private storage objects publicly.
• Align with Supabase migration/management approach already used in this repo.

Files to create or edit

• EDIT: /ProjectBeacon/ProjectBeacon/supabase/migrations/* (new migration/setup step)
• EDIT: /ProjectBeacon/ProjectBeacon/lib/storage/upload-project-document.ts
• EDIT: /ProjectBeacon/ProjectBeacon/lib/env.ts
• EDIT: /ProjectBeacon/ProjectBeacon/README.md
• EDIT: /ProjectBeacon/ProjectBeacon/HANDOFF.md

Expected output / interface

Fresh repo setup consistently provisions usable document storage so project file uploads work without manual infra patching.

Blocking Issues

• [PB-030] Align Document Access Schema With V0 API Contracts #71 (PB-030)

[justinch4n]

Blocked by dependency #71 (PB-030), which is still open in status:handoff and not yet completed/closed.

Per agent runner dependency policy, this issue cannot start until #71 is merged/closed.

Next action:

1. Merge/close [PB-030] Align Document Access Schema With V0 API Contracts #71 (PR [PB-030] Align document access schema with V0 API contracts #100)
2. Move [PB-045] Add reproducible Supabase storage bucket provisioning for project documents #96 back to status:ready
3. Resume implementation for reproducible storage bucket provisioning