docs(schema): document missing CI nodes

What does this MR do and why?

Documents the four CI/CD node types that are indexed and queryable but were missing from the schema reference: Deployment, Environment, JobMetadata, and Runner. Also corrects the total node count from 24 to 28.

Before, docs/source/remote/schema.md listed only Pipeline, Stage, and Job under CI/CD, so users couldn't discover the other four entities or build valid queries against them from the docs alone. Properties for each new node are sourced from config/ontology/nodes/ci/{deployment,environment,job_metadata,runner}.yaml.

Related Issues

Closes #652 (closed)

Testing

Performance Analysis

• This merge request does not introduce any performance regression. If a performance regression is expected, explain why.

Agent context — long-form analysis, file-by-file walkthroughs, profiler output, alternatives considered

• docs(schema): document missing CI nodes

Closes #652 (closed)