feat(ai): add CASTS for GeaFlow reasoning ability

.github/workflows/ci-py311.yml

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+  name: CASTS Python Tests
+
+  on:
+    pull_request:
+      paths:
+        - "geaflow-ai/plugins/casts/**"
+    push:
+      branches: ["master"]
+      paths:
+        - "geaflow-ai/plugins/casts/**"
+    workflow_dispatch:
+
+  jobs:
+    tests:
+      runs-on: ubuntu-latest
+      defaults:
+        run:
+          working-directory: geaflow-ai/plugins/casts
+      steps:
+        - uses: actions/checkout@v4
+        - uses: actions/setup-python@v5
+          with:
+            python-version: "3.11"
+        - name: Install uv
+          run: pip install uv
+        - name: Sync deps
+          run: uv sync
+        - name: Run tests
+          run: uv run pytest

geaflow-ai/plugins/casts/.gitignore

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+# Byte-compiled / optimized files
+__pycache__/
+*.py[cod]
+CASTS.egg-info/*
+
+# Environment variables
+.env
+
+# Virtual environment
+.venv/
+uv.lock
+
+# Logs
+/logs/
+
+# IDE / OS specific
+.vscode/
+.DS_Store
+
+# Data files
+data/real_graph_data/
+casts_traversal_path_req_*.png

geaflow-ai/plugins/casts/README.md

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+# CASTS (Context-Aware Strategy Cache System)
+
+CASTS is a strategy cache for graph traversal systems. It learns, stores, and
+retrieves traversal decisions (strategies) based on structural signatures,
+node properties, and goals, with optional LLM-driven guidance.
+
+## Name Origin
+
+CASTS stands for **Context-Aware Strategy Cache System**.
+
+## Design Goals
+
+- Cache traversal strategies (SKUs) to reduce repeated LLM calls.
+- Separate schema metadata from execution logic.
+- Support both synthetic and real-world graph data.
+- Keep the core cache logic deterministic and testable.
+
+## Module Layout
+
+- `core`: cache, schema, configuration, and core models
+- `data`: data sources and graph generation (synthetic + real)
+- `services`: embedding + LLM services
+- `simulation`: simulation engine and evaluation
+- `tests`: unit and integration tests
+
+## Repository Placement
+
+This module is intended to live under `geaflow-ai/plugins/casts` as a standalone
+plugin, with the Python package located at the module root.
+
+## Configuration (Required)
+
+The following environment variables are required. Missing values raise a
+`ValueError` at startup:
+
+- `EMBEDDING_ENDPOINT`
+- `EMBEDDING_APIKEY`
+- `EMBEDDING_MODEL`
+- `LLM_ENDPOINT`
+- `LLM_APIKEY`
+- `LLM_MODEL`
+
+You can use a local `.env` file for development. The code does not provide
+automatic fallbacks for missing credentials.
+
+## Real Data Loading
+
+The default loader reads CSV files from `data/real_graph_data` (or
+`real_graph_data`) and builds a directed graph. You can override this behavior
+by providing a custom loader:
+
+```python
+from data.graph_generator import GraphGeneratorConfig, GraphGenerator
+
+def my_loader(config: GraphGeneratorConfig):
+    # return nodes, edges
+    return {}, {}
+
+config = GraphGeneratorConfig(use_real_data=True, real_data_loader=my_loader)
+graph = GraphGenerator(config=config)
+```
+
+## Schema Updates
+
+`InMemoryGraphSchema` caches type-level labels. If you mutate nodes or edges
+after creation, call `mark_dirty()` or `rebuild()` before querying schema data.
+
+## Running a Simulation
+
+From the plugins directory (parent of this module):
+
+```bash
+cd /Users/kuda/code/geaflow/geaflow-ai/plugins
+uv sync
+python -m simulation.runner
+```
+
+## Tests
+
+Run tests locally:
+
+```bash
+uv sync
+pytest
+```
+
+There is no GitHub Actions workflow for this module by default.
+
+## Documentation
+
+- `docs/dependency_licenses.md`: Direct-dependency license summary and verification notes.
+
+## Dependency Mirrors
+
+This project does not hardcode PyPI mirrors. Configure mirrors in your
+environment or tooling if needed.
+
+## Third-Party Licenses
+
+See `docs/dependency_licenses.md` for a direct-dependency license summary.

geaflow-ai/plugins/casts/__init__.py

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+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+

geaflow-ai/plugins/casts/core/__init__.py

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+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+