feat: add parsing utilities and 8-tab chart infrastructure (Task 9.1)

- Create src/data_processing/parsing.py with parse_average_spacing(),
  parse_pathway_drugs(), and calculate_retention_rate()
- Add 8-tab bar to chart_card.py (Icicle, Market Share, Cost Effectiveness,
  Cost Waterfall, Sankey, Dosing, Heatmap, Duration)
- Add active-tab dcc.Store and tab switching callback in chart.py
- Remove Chart Views section from sidebar (now in tab bar)
- Lazy rendering: only active tab's chart is computed

dash_app/components/sidebar.py

@@ -19,9 +19,6 @@ def _svg_icon(svg_body):
 # SVG icon bodies (Feather-style)
 _ICONS = {
     "pathway": '<rect x="3" y="3" width="7" height="7"/><rect x="14" y="3" width="7" height="7"/><rect x="14" y="14" width="7" height="7"/><rect x="3" y="14" width="7" height="7"/>',
-    "icicle": '<rect x="3" y="3" width="18" height="4" rx="1"/><rect x="3" y="10" width="10" height="4" rx="1"/><rect x="3" y="17" width="6" height="4" rx="1"/>',
-    "sankey": '<path d="M6 3v18"/><path d="M18 3v18"/><path d="M6 8c6 0 6 5 12 5"/><path d="M6 16c4 0 4-3 12-3"/>',
-    "timeline": '<line x1="3" y1="12" x2="21" y2="12"/><circle cx="6" cy="12" r="2"/><circle cx="12" cy="12" r="2"/><circle cx="18" cy="12" r="2"/>',
 }
 
 
@@ -39,16 +36,6 @@ def make_sidebar():
                     _sidebar_item("Pathway Overview", "pathway", active=True),
                 ],
             ),
-            # Chart views section
-            html.Div(
-                className="sidebar__section",
-                children=[
-                    html.Div("Chart Views", className="sidebar__label"),
-                    _sidebar_item("Icicle Chart", "icicle", active=True),
-                    _sidebar_item("Sankey Diagram", "sankey", disabled=True),
-                    _sidebar_item("Timeline", "timeline", disabled=True),
-                ],
-            ),
             # Footer
             html.Div(
                 className="sidebar__footer",
@@ -62,13 +49,11 @@ def make_sidebar():
     )
 
 
-def _sidebar_item(label, icon_key, active=False, disabled=False, item_id=None):
+def _sidebar_item(label, icon_key, active=False, item_id=None):
     """Create a single sidebar navigation item."""
     class_name = "sidebar__item"
     if active:
         class_name += " sidebar__item--active"
-    if disabled:
-        class_name += " sidebar__item--disabled"
 
     props = {"className": class_name}
     if item_id: