Add Godot ClassDB API introspection

[Clubhouse1661]

Fixes #552

Summary

Adds version-correct Godot API introspection backed by the running editor’s ClassDB.

• Adds api_manage(op="get_class")
• Adds godot://class/{class_name}
• Returns class metadata: properties, hints, defaults, methods, signals, enums, constants, inheritance, and optional inheritors
• Keeps default payloads small with direct members only plus section pagination
• Documents that callers should page one requested section at a time
• Adds clear errors for project script class_name lookups, invalid sections, and negative limits
• Enriches resource_manage(op="get_info") with hint_string, property defaults, and property class names while keeping the Resource-only is_abstract field
• Shares fuzzy suggestion ranking for typos

Testing

• ruff check src tests
• Focused MCP/Python suite: 505 passed
• Live Godot 4.6.3 MCP suites: api 9/9, resource 41/41, node 131/131 passed

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[dsarno]

Reviewed with the branch checked out locally: ruff clean, 880 unit + 290 integration tests pass, and all 15 CI checks (including the Godot 4.3 canary) are green. I also verified the new ClassDB calls (class_get_property_default_value, is_class_enum_bitfield, class_get_integer_constant_enum, get_global_class_list) all exist in Godot 4.3, so the version floor is intact.

Overall this is solid — it follows the AGENTS.md tool-change checklist end to end, the VariantSerializer/FuzzySuggestions extractions are behavior-preserving, and the error UX (typo suggestions, script-class redirect to script_manage) is thoughtful. Five non-blocking comments inline.

Smaller follow-up candidates, not blocking: VariantSerializer is missing TYPE_PACKED_VECTOR4_ARRAY in its array branch (pre-existing, but cheap to fix while extracting; the type exists in 4.3+), and handlers/_property_errors.gd still carries its own similarity ranker that could move to FuzzySuggestions later.

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[Clubhouse1661]

Thanks for the review.
I addressed your feedback in a new commit 7c07fed:

• Dropped the unrelated editor.py reload-delay hunk.
• Documented that offset/limit pagination should be used one section at a time.
• Kept the resource_manage(op="get_info") defaults enrichment intentionally, updated the PR description, and added a BoxMesh.size default assertion.
• Removed is_abstract from general api_manage class output and added is_singleton; resource_manage(get_info) keeps its Resource-only is_abstract field.
• Negative limit now returns INVALID_PARAMS.
• Added TYPE_PACKED_VECTOR4_ARRAY serialization.

[dsarno]

Thank you @Clubhouse1661 — this is a great addition! Version-correct ClassDB introspection straight from the running editor closes a real gap, and the execution here was a pleasure to review: the tool + resource forms follow the repo conventions exactly, the error UX (typo suggestions, the script_manage redirect for project script classes) is genuinely thoughtful, and every round of review feedback came back addressed with tests. Much appreciated! 🎉

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