feat(examples): Modernize example data loading with Parquet and YAML configs (#36538)

Co-authored-by: Claude <noreply@anthropic.com>

UPDATING.md

@@ -24,6 +24,41 @@ assists people when migrating to a new version.
 
 ## Next
 
+### Example Data Loading Improvements
+
+#### New Directory Structure
+Examples are now organized by name with data and configs co-located:
+```
+superset/examples/
+├── _shared/              # Shared database & metadata configs
+├── birth_names/          # Each example is self-contained
+│   ├── data.parquet     # Dataset (Parquet format)
+│   ├── dataset.yaml     # Dataset metadata
+│   ├── dashboard.yaml   # Dashboard config (optional)
+│   └── charts/          # Chart configs (optional)
+└── ...
+```
+
+#### Simplified Parquet-based Loading
+- Auto-discovery: create `superset/examples/my_dataset/data.parquet` to add a new example
+- Parquet is an Apache project format: compressed (~27% smaller), self-describing schema
+- YAML configs define datasets, charts, and dashboards declaratively
+- Removed Python-based data generation from individual example files
+
+#### Test Data Reorganization
+- Moved `big_data.py` to `superset/cli/test_loaders.py` - better reflects its purpose as a test utility
+- Fixed inverted logic for `--load-test-data` flag (now correctly includes .test.yaml files when flag is set)
+- Clarified CLI flags:
+  - `--force` / `-f`: Force reload even if tables exist
+  - `--only-metadata` / `-m`: Create table metadata without loading data
+  - `--load-test-data` / `-t`: Include test dashboards and .test.yaml configs
+  - `--load-big-data` / `-b`: Generate synthetic stress-test data
+
+#### Bug Fixes
+- Fixed numpy array serialization for PostgreSQL (converts complex types to JSON strings)
+- Fixed KeyError for `allow_csv_upload` field in database configs (now optional with default)
+- Fixed test data loading logic that was incorrectly filtering files
+
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