refactor(viz-platform): extract skills and slim commands

Extract shared knowledge from 10 commands into 7 reusable skills:
- mcp-tools-reference.md: All viz-platform MCP tool signatures
- theming-system.md: Theme tokens, CSS variables, color palettes
- accessibility-rules.md: WCAG contrast, color-blind safe palettes
- dmc-components.md: DMC categories, validation, common props
- responsive-design.md: Breakpoints, mobile-first, grid config
- chart-types.md: Plotly chart types, export formats, resolution
- layout-templates.md: Dashboard templates, filter types

All commands now reference skills via "Skills to Load" section.
Commands reduced from 1396 lines total to 427 lines (69% reduction).

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

plugins/viz-platform/commands/chart.md

@@ -4,18 +4,18 @@ description: Create a Plotly chart with theme integration
 
 # Create Chart
 
+## Skills to Load
+- skills/mcp-tools-reference.md
+- skills/chart-types.md
+
 ## Visual Output
 
-When executing this command, display the plugin header:
-
 ```
-┌──────────────────────────────────────────────────────────────────┐
-│  🎨 VIZ-PLATFORM · Chart Builder                                  │
-└──────────────────────────────────────────────────────────────────┘
++------------------------------------------------------------------+
+|  VIZ-PLATFORM - Chart Builder                                    |
++------------------------------------------------------------------+
 ```
 
-Then proceed with the chart creation.
-
 Create a Plotly chart with automatic theme token application.
 
 ## Usage
@@ -26,73 +26,16 @@ Create a Plotly chart with automatic theme token application.
 
 ## Arguments
 
-- `type` (required): Chart type - one of: line, bar, scatter, pie, area, histogram, box, heatmap, sunburst, treemap
-
-## Examples
-
-```
-/chart line
-/chart bar
-/chart scatter
-/chart pie
-```
+- `type` (required): line, bar, scatter, pie, area, histogram, box, heatmap, sunburst, treemap
 
 ## Tool Mapping
 
-This command uses the `chart_create` MCP tool:
-
 ```python
-chart_create(
-    chart_type="line",
-    data_ref="df_sales",          # Reference to loaded DataFrame
-    x="date",                      # X-axis column
-    y="revenue",                   # Y-axis column
-    color=None,                    # Optional: column for color grouping
-    title="Sales Over Time",       # Optional: chart title
-    theme=None                     # Optional: theme name to apply
-)
+chart_create(chart_type="line", data_ref="df", x="date", y="value", theme=None)
 ```
 
-## Workflow
+## Related Commands
 
-1. **User invokes**: `/chart line`
-2. **Agent asks**: Which DataFrame to use? (list available with `list_data` from data-platform)
-3. **Agent asks**: Which columns for X and Y axes?
-4. **Agent asks**: Any grouping/color column?
-5. **Agent creates**: Chart with `chart_create` tool
-6. **Agent returns**: Plotly figure JSON ready for rendering
-
-## Chart Types
-
-| Type | Best For |
-|------|----------|
-| `line` | Time series, trends |
-| `bar` | Comparisons, categories |
-| `scatter` | Correlations, distributions |
-| `pie` | Part-to-whole relationships |
-| `area` | Cumulative trends |
-| `histogram` | Frequency distributions |
-| `box` | Statistical distributions |
-| `heatmap` | Matrix correlations |
-| `sunburst` | Hierarchical data |
-| `treemap` | Hierarchical proportions |
-
-## Theme Integration
-
-Charts automatically inherit colors from the active theme:
-- Primary color for main data
-- Color palette for multi-series
-- Font family and sizes
-- Background colors
-
-Override with explicit theme:
-```python
-chart_create(chart_type="bar", ..., theme="my-dark-theme")
-```
-
-## Output
-
-Returns Plotly figure JSON that can be:
-- Rendered in a Dash app
-- Saved as HTML/PNG
-- Embedded in a layout component
+- `/chart-export {format}` - Export chart to image
+- `/theme {name}` - Apply theme to charts
+- `/dashboard` - Create layout with charts