Create comprehensive test fixture module to enable testing Sentinel Graph
functionality without requiring live Azure credentials or actual threat
intelligence data. This improves developer experience and enables faster
test iteration.

**What changed:**

- Created `graphistry/tests/fixtures/` package with synthetic response data
- Added `sentinel_graph_responses.py` with 9 fixture functions covering:
  - Minimal/simple graphs for basic testing
  - Duplicate node scenarios for deduplication logic
  - Malformed JSON for error handling validation
  - Empty responses for edge case coverage
  - Complex multi-type graphs for real-world simulation
  - Orphan edges, special characters, and null properties
- Updated `test_sentinel_graph.py` to use fixtures instead of hardcoded constants
- Reformatted notebook cells (Jupyter format standardization)

**Benefits:**

- Tests can run without Azure credentials or Sentinel Graph instance
- Fixtures mimic actual API response structure (Graph.Nodes + RawData.Rows)
- Easier to add new test cases by creating additional fixtures
- Validates parsing logic across diverse response scenarios
- All fixtures are JSON-serializable and structure-validated

**Testing:**

All 9 fixtures validated successfully with proper response structure.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

The Microsoft Sentinel Graph API returns fields with sys_* prefix
(sys_sourceId, sys_targetId, sys_label) instead of the underscore
prefix (_sourceId, _targetId, _label) that was originally expected.

- Update node/edge extraction to detect both _* and sys_* field formats
- Dynamically capture all properties from nodes and edges instead of
  hardcoding specific fields
- Normalize key fields (id, label, source, target, edge) while
  preserving all original properties
- Add test fixture mimicking actual Sentinel Graph API response format
- Add tests for sys_* field format parsing

Enable cleaner API usage without requiring bind():
  graphistry.configure_sentinel_graph('instance')
  graphistry.sentinel_graph(query)

Changes:
- Add GraphistryClient wrapper methods for sentinel_graph functions
- Export sentinel_graph methods at module level in pygraphistry.py
- Re-export in __init__.py for public API access
- Update docstring examples to use module-level pattern

Security: No additional risk - module-level access uses same session
model as bind() pattern. Tokens and credentials remain protected.

Microsoft moved Sentinel custom graph to public preview with a new
response schema. Updates the plugin to match:

- Rewrite response parsing for new envelope: result.graph.{nodes,edges}
  and result.rawData.tables (replacing the old Graph/RawData format)
- Add responseFormats request parameter (default: ["Graph"])
- Add sentinel_graph_list() to discover available graph instances via
  GET /graphs/graph-instances?graphTypes=Custom
- Remove sys_* / JSON-encoded-string field handling (pre-preview only)
- Rewrite test fixtures and tests for new schema; add TestSentinelGraphList,
  TestResponseFormats, and TestTableFormatParsing test classes
- Update demo notebook with list-then-configure pattern and responseFormats example

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

# Conflicts:
#	setup.py

- Add empty 'outputs' and 'execution_count' to two code cells in
  sentinel_graph_examples.ipynb (cells 7 and 9). nbformat 4 requires
  both keys on every code cell; nbsphinx errored with
  AttributeError: outputs during RTD's sphinx-build, killing the docs
  build after the pytz import was resolved upstream.
- Add azure.core.* and azure.identity to mypy.ini ignore_missing_imports.
  Mirrors the existing azure.kusto.* entry. Without these, mypy 1.20
  flags the 'azure.core.credentials' and 'azure.identity' imports in
  sentinel_graph.py / sentinel_graph_types.py as missing stubs, failing
  python-lint-types CI on every Python version.

Verified locally: ruff/mypy/pytest all green; nbformat.validate passes;
'import graphistry' loads cleanly.

Return the locally-bound token (typed 'str') instead of cfg._token
(typed 'Optional[str]'). Functionally equivalent — token is assigned
to cfg._token on the previous line — but mypy 1.14 (the pinned mypy
on the Python 3.8 lockfile) does not narrow the field-access form and
flagged: 'Incompatible return value type (got str | None, expected str)'.

mypy 1.20+ (3.10+ lockfiles) accepted the original code, which is why
the failure was 3.8-specific. Verified clean with both mypy 1.14 and
1.20.2; sentinel-graph tests still pass.