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.

app/utils.py

@@ -0,0 +1,45 @@
+"""
+Shared UI utilities for the Palladium Streamlit app.
+
+Kept in a separate module so that ``app.main`` and ``app.views.*`` can both
+import from here without creating a circular dependency.
+"""
+
+from __future__ import annotations
+
+import streamlit as st
+
+# ---------------------------------------------------------------------------
+# Bootstrap Icons — injected once at the top of every page render.
+# Using the CDN stylesheet so no npm/build step is needed.
+# ---------------------------------------------------------------------------
+_BI_CSS = """
+<link
+  rel="stylesheet"
+  href="https://cdn.jsdelivr.net/npm/bootstrap-icons@1.11.3/font/bootstrap-icons.min.css"
+/>
+<style>
+  /* Tighten up the default Streamlit header spacing */
+  .block-container { padding-top: 1.5rem; }
+  /* Make BI icons align nicely with surrounding text */
+  .bi { vertical-align: -0.125em; }
+</style>
+"""
+
+
+def inject_icons() -> None:
+    """Inject Bootstrap Icons CSS (idempotent — Streamlit deduplicates identical HTML)."""
+    st.markdown(_BI_CSS, unsafe_allow_html=True)
+
+
+def icon(name: str, *, cls: str = "") -> str:
+    """Return an inline Bootstrap Icon ``<i>`` tag.
+
+    Usage::
+
+        st.markdown(icon("bar-chart") + " Financial Summary", unsafe_allow_html=True)
+
+    See the full icon catalogue at https://icons.getbootstrap.com/
+    """
+    extra = f" {cls}" if cls else ""
+    return f'<i class="bi bi-{name}{extra}"></i>'