Document Event Study support in effect_summary

Added Event Study to the experiment support table in reporting_statistics.md and updated AGENTS.md to instruct updating the table when adding new experiment types.

Author: drbenvincent

AGENTS.md

@@ -24,6 +24,7 @@
   - `docs/source/index.md` (documentation website homepage)
 
   When adding major new features to the Features table or making other content changes, update **both files**. The Features table lists all quasi-experimental methods supported by CausalPy.
+- **Reporting statistics**: When adding new experiment types, update the "Experiment Support" table in `docs/source/knowledgebase/reporting_statistics.md` to document `effect_summary()` support status for the new experiment.
 - **Structure**: Notebooks (how-to examples) go in `docs/source/notebooks/`, knowledgebase (educational content) goes in `docs/source/knowledgebase/`
 - **Notebook naming**: Use pattern `{method}_{model}.ipynb` (e.g., `did_pymc.ipynb`, `rd_skl.ipynb`), organized by causal method
 - **Notebook index**: New notebooks must be added to `docs/source/notebooks/index.md` under the appropriate `toctree` section for them to appear in the rendered documentation

docs/source/knowledgebase/reporting_statistics.md

@@ -26,6 +26,7 @@ The `effect_summary()` method is available for the following experiment types:
 | Regression Kink | ✅ Full support | ❌ Not implemented |
 | Interrupted Time Series | ✅ Full support | ✅ Full support |
 | Synthetic Control | ✅ Full support | ✅ Full support |
+| Event Study | ✅ Full support | ✅ Full support |
 | PrePostNEGD | ❌ Use `.summary()` instead | ❌ Use `.summary()` instead |
 | Instrumental Variable | ❌ Not available | ❌ Not available |
 | Inverse Propensity Weighting | ❌ Not available | ❌ Not available |