refactor: remove Trends tab from Patient Pathways (Task E.1)

Remove trends tab, metric toggle, render helper, and callback I/O
from Patient Pathways view. Trends will be re-added as a standalone
3rd view in E.2-E.4. Preserved get_trend_data() and create_trend_figure()
for reuse.

dash_app/components/chart_card.py

@@ -14,7 +14,6 @@ TAB_DEFINITIONS = [
     ("network", "Network"),
     ("timeline", "Timeline"),
     ("doses", "Doses"),
-    ("trends", "Trends"),
 ]
 
 # Full set retained for Trust Comparison dashboard (Phase 10.8)
@@ -95,23 +94,6 @@ def make_chart_card():
                             ),
                         ],
                     ),
-                    # Trends metric toggle — visible only when trends tab active
-                    html.Div(
-                        id="trends-metric-wrapper",
-                        style={"display": "none"},
-                        children=[
-                            dmc.SegmentedControl(
-                                id="trends-metric-toggle",
-                                data=[
-                                    {"value": "patients", "label": "Patients"},
-                                    {"value": "total_cost", "label": "Cost"},
-                                    {"value": "cost_pp_pa", "label": "Cost p.a."},
-                                ],
-                                value="patients",
-                                size="xs",
-                            ),
-                        ],
-                    ),
                 ],
             ),
             # Chart area with loading spinner