docs(knowledge-graph): document Manual Declarations and the JSON import

[mangglesh]

Summary

Documents the Knowledge Graph's Manual Declarations: adding dependencies and resources the collectors cannot see, one at a time or from a single JSON document. The feature ships in nudgebee/nudgebee-enterprise#40384. That PR merges the old Manual Dependencies and Manual Nodes tabs into one, and replaces their two CSV imports with a single JSON import.

Stacked on #868. That PR turns the Knowledge Graph page into a section. This one adds a page to it. Merge #868 first; this PR then retargets to main on its own.

Merge this after nudgebee/nudgebee-enterprise#40384 is merged and released. Until then, these docs describe a tab that production doesn't have.

• New page: Semantic Knowledge Graph → Manual Declarations. It covers:
  • what you can declare, and when a declared node merges with a collected one;
  • node and dependency statuses;
  • the JSON format, with field tables and an example;
  • what an import reports;
  • permissions and removal.
• Links: the Overview, Where the Data Comes From, and How NudgeBee Uses the Graph pages now point to it.
• API docs: kg_import_manual_dependencies is replaced by kg_create_manual_declarations, and the seven kg_*_manual_node* actions are added. The rows use the routing table's own descriptions, so the next regeneration produces the same text.

Type of change

• New documentation page
• Update to existing documentation

Checklist

• I ran npm run build locally and the site builds without errors
• I ran npm run lint locally and lint passes
• Internal links work; new external links open the correct page
• My commits are signed off (DCO — git commit -s)
• I read CONTRIBUTING.md

Screenshots (if visual changes)

The four new images are in doc-server/docs/features/img/knowledge-graph-*.png, and the new page uses them. They show example names on a dev tenant, cropped to the dialog or section, with no endpoints or user names visible.

Additional notes

• Release notes: this PR adds no release-notes or product-update entry. Those are written when the release that includes #40384 is cut.
• API docs generator: the generator escapes only | and \ in action descriptions, so a { or < in a routing-table comment breaks the MDX build. The new action's comment originally contained one. It now sits in a code span, fixed at the source in #40384.

[gemini-code-assist]

Code Review

This pull request restructures the Semantic Knowledge Graph documentation by moving it into a dedicated directory and adding comprehensive documentation for the new Manual Declarations feature. It updates relative links across various files, introduces a new category configuration, and documents several new API actions for manual node and dependency management. Feedback on the changes includes a correction to use US English spelling ("favor" instead of "favour") in the API documentation description for kg_apply_manual_node_merge.