Add JSON Schema Documentation for SEPEX Processes

[sclaw]

This PR resolves #120 by adding JSON schema and human-readable documentation for SEPEX process YAML files.

Changes

1. Added process.json schema definition covering all process fields (info, host, command, config, inputs, outputs)
2. Added build-time generation of HTML documentation using json-schema-for-humans
3. Added API endpoints:
   • /schemas/process - serves human-readable HTML documentation
   • /schemas/process.json - serves machine-readable JSON schema
4. Updated Dockerfile to install Python tools and run schema generation during build

Demo of new endpoint at /schemas/process