docs: migrate module documentation to single source of truth

Move 39 documentation files from top-level docs/ into each module's
docs/ folder, accessible via symlinks from docs/modules/. Create
data-model.md files for 10 modules with full schema documentation.
Replace originals with redirect stubs. Remove empty guide stubs.

Modules migrated: tenancy, billing, loyalty, marketplace, orders,
messaging, cms, catalog, inventory, hosting, prospecting.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/modules/prospecting/docs/index.md

@@ -0,0 +1,58 @@
+# Prospecting
+
+Lead discovery, scoring, and campaign management for Luxembourg businesses.
+
+## Overview
+
+| Aspect | Detail |
+|--------|--------|
+| Code | `prospecting` |
+| Classification | Optional |
+| Dependencies | None |
+| Status | Active |
+
+## Features
+
+- `domain_scanning` — Automated domain and website scanning
+- `offline_capture` — Offline business data capture
+- `opportunity_scoring` — Lead scoring algorithms
+- `campaign_management` — Outreach campaign management
+- `lead_export` — Lead data export
+
+## Permissions
+
+| Permission | Description |
+|------------|-------------|
+| `prospecting.view` | View prospects |
+| `prospecting.manage` | Manage prospect data |
+| `prospecting.scan` | Run domain scans |
+| `prospecting.campaigns` | Manage campaigns |
+| `prospecting.export` | Export prospect data |
+
+## Data Model
+
+- **Campaign** — Outreach campaign records
+- **Interaction** — Prospect interaction tracking
+- **PerformanceProfile** — Website performance analysis
+- **ProspectContact** — Prospect contact information
+
+## API Endpoints
+
+| Method | Path | Description |
+|--------|------|-------------|
+| `*` | `/api/v1/admin/prospects/*` | Prospect management |
+| `*` | `/api/v1/admin/campaigns/*` | Campaign management |
+| `*` | `/api/v1/admin/leads/*` | Lead management |
+| `*` | `/api/v1/admin/enrichment/*` | Data enrichment |
+| `*` | `/api/v1/admin/interactions/*` | Interaction tracking |
+
+## Configuration
+
+No module-specific configuration.
+
+## Additional Documentation
+
+- [Database Schema](database.md) — Database schema and entity relationships
+- [Scoring Algorithm](scoring.md) — Lead scoring algorithm details
+- [Research Findings](research-findings.md) — Research findings and analysis
+- [User Journeys](user-journeys.md) — Prospecting user journeys