feat(mcp): add list and get tools for annotation layers and annotations

[aminghadersohi]

SUMMARY

Adds 4 new MCP tools in a new superset/mcp_service/annotation_layer/ domain:

• list_annotation_layers — list annotation layers with filtering, search, and 1-based pagination
• get_annotation_layer_info — get annotation layer details by ID
• list_layer_annotations — list annotations within a layer (requires layer_id to scope results)
• get_layer_annotation_info — get a single annotation by layer_id + annotation_id, with layer-membership verification

The annotation tools mirror the pattern used by database/, dashboard/, and dataset/ domains: Pydantic request/response schemas, ModelListCore for listings, DAO-based lookups, ToolAnnotations, and event_logger instrumentation.

For annotations, layer_id is a required parameter that scopes all results to the parent layer — mirroring the Superset REST API structure (GET /annotation_layer/{layer_pk}/annotation/).

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

N/A (backend-only MCP tool additions)

TESTING INSTRUCTIONS

1. Run unit tests:

   pytest tests/unit_tests/mcp_service/annotation_layer/
   

2. Connect an MCP client and call:
   • list_annotation_layers({}) — lists all annotation layers
   • get_annotation_layer_info({"id": <id>}) — retrieves a specific layer
   • list_layer_annotations({"layer_id": <id>}) — lists annotations in a layer
   • get_layer_annotation_info({"layer_id": <id>, "annotation_id": <id>}) — retrieves a specific annotation

ADDITIONAL INFORMATION

• Has associated issue:
• Required feature flags:
• Changes UI
• Includes DB Migration
• Introduces new feature or API
• Removes existing feature or API

[codecov]

Codecov Report

❌ Patch coverage is 65.62500% with 88 lines in your changes missing coverage. Please review.
✅ Project coverage is 63.83%. Comparing base (73f66e4) to head (6e71872).
⚠️ Report is 11 commits behind head on master.

Files with missing lines	Patch %	Lines
...annotation_layer/tool/get_layer_annotation_info.py	29.03%	22 Missing ⚠️
...ce/annotation_layer/tool/list_layer_annotations.py	39.39%	20 Missing ⚠️
superset/mcp_service/annotation_layer/schemas.py	87.31%	16 Missing and 1 partial ⚠️
...ce/annotation_layer/tool/list_annotation_layers.py	42.85%	16 Missing ⚠️
...annotation_layer/tool/get_annotation_layer_info.py	43.47%	13 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #40303      +/-   ##
==========================================
- Coverage   64.14%   63.83%   -0.32%     
==========================================
  Files        2592     2598       +6     
  Lines      138846   140183    +1337     
  Branches    32201    32492     +291     
==========================================
+ Hits        89069    89488     +419     
- Misses      48245    49131     +886     
- Partials     1532     1564      +32     

Flag	Coverage Δ
hive	39.15% <65.62%> (-0.18%)	⬇️
mysql	58.28% <65.62%> (-0.58%)	⬇️
postgres	58.36% <65.62%> (-0.58%)	⬇️
presto	40.79% <65.62%> (-0.21%)	⬇️
python	59.89% <65.62%> (-0.62%)	⬇️
sqlite	58.01% <65.62%> (-0.58%)	⬇️
unit	100.00% <ø> (ø)

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[aminghadersohi]

Superseded by #40342 (branch renamed to follow amin/ convention).