feat: Complete Phase 5 dashboard implementation

Implement full 5-tab Toronto Neighbourhood Dashboard with real data
connectivity:

Dashboard Structure:
- Overview tab with livability scores and rankings
- Housing tab with affordability metrics
- Safety tab with crime statistics
- Demographics tab with population/income data
- Amenities tab with parks, schools, transit

Figure Factories (portfolio_app/figures/):
- bar_charts.py: ranking, stacked, horizontal bars
- scatter.py: scatter plots, bubble charts
- radar.py: spider/radar charts
- demographics.py: donut, age pyramid, income distribution

Service Layer (portfolio_app/toronto/services/):
- neighbourhood_service.py: queries dbt marts for all tab data
- geometry_service.py: generates GeoJSON from PostGIS
- Graceful error handling when database unavailable

Callbacks (portfolio_app/pages/toronto/callbacks/):
- map_callbacks.py: choropleth updates, map click handling
- chart_callbacks.py: supporting chart updates
- selection_callbacks.py: dropdown handlers, KPI updates

Data Pipeline (scripts/data/):
- load_toronto_data.py: orchestration script with CLI flags

Lessons Learned:
- Graceful error handling in service layers
- Modular callback structure for multi-tab dashboards
- Figure factory pattern for reusable charts

Closes: #64, #65, #66, #67, #68, #69, #70

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/project-lessons-learned/sprint-9-10-modular-callback-structure.md

@@ -0,0 +1,45 @@
+# Sprint 9-10 - Modular Callback Structure for Multi-Tab Dashboards
+
+## Context
+Implementing a 5-tab Toronto Neighbourhood Dashboard with multiple callbacks per tab (map updates, chart updates, KPI updates, selection handling).
+
+## Problem
+Initial callback implementation approach would have placed all callbacks in a single file, leading to:
+- A monolithic file with 500+ lines
+- Difficult-to-navigate code
+- Callbacks for different tabs interleaved
+- Testing difficulties
+
+## Solution
+Organized callbacks into three focused modules:
+
+```
+callbacks/
+├── __init__.py              # Imports all modules to register callbacks
+├── map_callbacks.py         # Choropleth updates, map click handling
+├── chart_callbacks.py       # Supporting chart updates (scatter, trend, donut)
+└── selection_callbacks.py   # Dropdown population, KPI updates
+```
+
+Key patterns:
+1. **Group by responsibility**, not by tab - all map-related callbacks together
+2. **Use noqa comments** for imports that register callbacks as side effects
+3. **Share helper functions** (like `_empty_chart()`) within modules
+
+```python
+# callbacks/__init__.py
+from . import (
+    chart_callbacks,  # noqa: F401
+    map_callbacks,  # noqa: F401
+    selection_callbacks,  # noqa: F401
+)
+```
+
+## Prevention
+- **Plan callback organization before implementation** - sketch which callbacks go where
+- **Group by function, not by feature** - keeps related logic together
+- **Keep modules under 400 lines** - split if exceeding
+- **Test imports early** - verify callbacks register correctly
+
+## Tags
+dash, callbacks, architecture, python, code-organization, maintainability