fix: escape dollar signs in Dokploy project-level variables

Docker Compose interprets $ as variable substitution, so we need to escape
Dokploy's project-level variable syntax by doubling the dollar sign.

Changes:
- docker-compose.*.yml: ${{project.VAR}} → $${{project.VAR}}
- Updated DOKPLOY_DEPLOYMENT.md with correct syntax and explanation
- Updated SHARED_PROJECT_DEPLOYMENT.md with correct syntax and explanation

This fixes the 'You may need to escape any $ with another $' error when
deploying via Dokploy.

Evidence: Tested in Dokploy deployment - error resolved with $$ escaping.

docker-compose.dev.yml

@@ -15,8 +15,8 @@ services:
       - STACK_DOMAIN_SUFFIX=${STACK_DOMAIN_SUFFIX:-ai.flexinit.nl}
       - STACK_IMAGE=${STACK_IMAGE:-git.app.flexinit.nl/flexinit/agent-stack:latest}
       - RESERVED_NAMES=${RESERVED_NAMES:-admin,api,www,root,system,test,demo,portal}
-      - SHARED_PROJECT_ID=${{project.SHARED_PROJECT_ID}}
-      - SHARED_ENVIRONMENT_ID=${{project.SHARED_ENVIRONMENT_ID}}
+      - SHARED_PROJECT_ID=$${{project.SHARED_PROJECT_ID}}
+      - SHARED_ENVIRONMENT_ID=$${{project.SHARED_ENVIRONMENT_ID}}
     env_file:
       - .env
     restart: unless-stopped

docker-compose.prod.yml

@@ -15,8 +15,8 @@ services:
       - STACK_DOMAIN_SUFFIX=${STACK_DOMAIN_SUFFIX:-ai.flexinit.nl}
       - STACK_IMAGE=${STACK_IMAGE:-git.app.flexinit.nl/flexinit/agent-stack:latest}
       - RESERVED_NAMES=${RESERVED_NAMES:-admin,api,www,root,system,test,demo,portal}
-      - SHARED_PROJECT_ID=${{project.SHARED_PROJECT_ID}}
-      - SHARED_ENVIRONMENT_ID=${{project.SHARED_ENVIRONMENT_ID}}
+      - SHARED_PROJECT_ID=$${{project.SHARED_PROJECT_ID}}
+      - SHARED_ENVIRONMENT_ID=$${{project.SHARED_ENVIRONMENT_ID}}
     env_file:
       - .env
     restart: unless-stopped

docker-compose.staging.yml

@@ -15,8 +15,8 @@ services:
       - STACK_DOMAIN_SUFFIX=${STACK_DOMAIN_SUFFIX:-ai.flexinit.nl}
       - STACK_IMAGE=${STACK_IMAGE:-git.app.flexinit.nl/flexinit/agent-stack:latest}
       - RESERVED_NAMES=${RESERVED_NAMES:-admin,api,www,root,system,test,demo,portal}
-      - SHARED_PROJECT_ID=${{project.SHARED_PROJECT_ID}}
-      - SHARED_ENVIRONMENT_ID=${{project.SHARED_ENVIRONMENT_ID}}
+      - SHARED_PROJECT_ID=$${{project.SHARED_PROJECT_ID}}
+      - SHARED_ENVIRONMENT_ID=$${{project.SHARED_ENVIRONMENT_ID}}
     env_file:
       - .env
     restart: unless-stopped

docs/DOKPLOY_DEPLOYMENT.md

@@ -143,13 +143,15 @@ In the shared project (`ai-stack-portal`), add these **project-level environment
 
 The portal's docker-compose files use Dokploy's variable syntax to reference these:
 
-```yaml
-environment:
-  - SHARED_PROJECT_ID=${{project.SHARED_PROJECT_ID}}
-  - SHARED_ENVIRONMENT_ID=${{project.SHARED_ENVIRONMENT_ID}}
-```
+   ```yaml
+   environment:
+     - SHARED_PROJECT_ID=$${{project.SHARED_PROJECT_ID}}
+     - SHARED_ENVIRONMENT_ID=$${{project.SHARED_ENVIRONMENT_ID}}
+   ```
 
-**This syntax `${{project.VARIABLE}}` tells Dokploy**: "Get this value from the project-level environment variables"
+**This syntax `$${{project.VARIABLE}}` tells Dokploy**: "Get this value from the project-level environment variables"
+   
+**Note**: The double `$$` is required to escape the dollar sign in Docker Compose files.
 
 ### Important Notes
 

docs/SHARED_PROJECT_DEPLOYMENT.md

@@ -17,7 +17,7 @@ The AI Stack Deployer portal deploys **all user AI stacks to a single shared Dok
 │  📦 Portal Application: ai-stack-deployer-prod                 │
 │     ├─ Domain: portal.ai.flexinit.nl                           │
 │     ├─ Image: git.app.flexinit.nl/.../ai-stack-deployer:latest│
-│     └─ Env: SHARED_PROJECT_ID=${{project.SHARED_PROJECT_ID}}  │
+│     └─ Env: SHARED_PROJECT_ID=$${{project.SHARED_PROJECT_ID}}  │
 │                                                                 │
 │  ───────────────────────────────────────────────────────────── │
 │                                                                 │
@@ -56,10 +56,12 @@ When a user submits a stack name (e.g., "john-dev"), the portal:
 2. **These are set via Dokploy's project-level variables**:
    ```yaml
    environment:
-     - SHARED_PROJECT_ID=${{project.SHARED_PROJECT_ID}}
-     - SHARED_ENVIRONMENT_ID=${{project.SHARED_ENVIRONMENT_ID}}
+     - SHARED_PROJECT_ID=$${{project.SHARED_PROJECT_ID}}
+     - SHARED_ENVIRONMENT_ID=$${{project.SHARED_ENVIRONMENT_ID}}
    ```
    
+   **Note**: The double `$$` is required to escape the dollar sign in Docker Compose.
+
 ### Step 2: Portal Deploys to Shared Project
 
 Instead of creating a new project, the portal: