feat: add locale formatting config and update notebook outputs

Add configurable locale/display formatting environment variables
(`PALLADIUM_CURRENCY_SYMBOL`, `PALLADIUM_THOUSANDS_SEP`,
`PALLADIUM_DECIMAL_SEP`) to support regional number formatting in the
Streamlit app. Update `.env.example` with documentation for these new
variables.

Also refresh `00_setup.ipynb` with current execution outputs reflecting
a live Athena connection with report templates, a selected client
(Global Guardian Insurance, ID=2), and resolved NameError in assumption
override cells.

README.md

@@ -261,7 +261,7 @@ palladium/
 │   └── __main__.py
 ├── app/                               # Streamlit UI — works with any TEI study
 │   ├── main.py                        # entry point
-│   ├── pages/                         # benefits, costs, summary, versions
+│   ├── views/                         # benefits, costs, summary, versions (NOT `pages/` — avoids Streamlit auto-multipage)
 │   └── components/                    # tables, charts
 ├── studies/                           # One folder per TEI engagement
 │   └── 202602_AmazonConnect/