Publish a Mock and Placeholder Inventory

[Cedarich]

Complexity: Medium (150)

Description
Mock implementations remain scattered across every service, and there is no single place that
records which paths are real and which are simulated. A contributor cannot currently tell whether a
feature works or merely appears to. Concrete examples include
app/backend/src/claims/claims.service.ts generating package ids via generateMockPackageId,
app/backend/src/aid/aid.service.ts hardcoding 'mock-c-id',
app/backend/src/evidence/evidence.service.ts simulating object storage,
app/backend/src/notifications/notifications.processor.ts logging instead of delivering,
app/frontend/src/lib/mock-api/ still imported by production components, and
app/mobile/src/services/mockData.ts backing HealthScreen and AidDetailsScreen.

Produce a maintained inventory so the remaining gap between demo and production is legible.

Acceptance Criteria

• A document in doc/ lists every known mock, stub, and placeholder with its file path
• Each entry states what is simulated, what depends on it, and what replacing it requires
• Entries link to the tracking issue where one exists
• The document distinguishes intentional test doubles from unfinished production paths
• The process for keeping the inventory current is stated