feat: add OpenSpec proposal for FTPS deployment

Create proposal for automated deployment script that uploads the Hugo site
to www.markusgraf.ch via FTPS. Includes:
- Deployment capability spec with 4 main requirements
- Implementation tasks for scripts/deploy.sh
- Secure credential management via environment variables

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

openspec/changes/add-ftps-deployment/proposal.md

@@ -0,0 +1,18 @@
+# Change Proposal: add-ftps-deployment
+
+## Why
+Currently there is no automated way to deploy the built Hugo site to the production server. Manual file transfers are error-prone and time-consuming. This change adds a deployment script to automate FTPS uploads to www.markusgraf.ch.
+
+## What Changes
+- Add deployment script `scripts/deploy.sh` that uploads `public/` directory via FTPS
+- Use environment variable `FTPS_PASSWORD` for secure credential management
+- Implement prerequisite checks (public/ exists, lftp installed, credentials set)
+- Add error handling and progress reporting
+- Update documentation with deployment instructions
+
+## Impact
+- Affected specs: New `deployment` capability
+- Affected code: New file `scripts/deploy.sh`
+- Dependencies: Requires `lftp` tool to be installed
+- Configuration: User must set `FTPS_PASSWORD` environment variable
+- No changes to existing Hugo templates, content, or build process