Add PENPOT_INTERNAL_URI environment variable to the exporter. This allows
separating the URI used for internal communication (headless browser to
frontend) from the public URI used for resource references in exported SVGs.
Previously, PENPOT_PUBLIC_URI served both purposes, which caused exported
SVGs to contain broken font URLs when the internal Docker address was used.
Changes:
- Add :internal-uri to exporter config schema with fallback to :public-uri
- Add get-internal-uri helper function
- Use internal-uri for browser navigation in SVG/PDF/bitmap renderers
- Post-process SVG output to replace internal URI with public URI
- Use internal-uri for backend API calls in resource handler
- Log both URIs on startup
- Update docker-compose.yaml to use both variables
- Document the new variable in configuration.md
Closes#10627
AI-assisted-by: mimo-v2.5-pro
