refactor: rename command files for namespace consistency

BREAKING CHANGE: All generic command names now prefixed with plugin namespace.
See CHANGELOG.md v7.0.0 for complete rename map.

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

plugins/viz-platform/commands/viz-chart-export.md

@@ -0,0 +1,42 @@
+---
+description: Export a Plotly chart to PNG, SVG, or PDF format
+---
+
+# Export Chart
+
+## Skills to Load
+- skills/mcp-tools-reference.md
+- skills/chart-types.md
+
+## Visual Output
+
+```
++------------------------------------------------------------------+
+|  VIZ-PLATFORM - Chart Export                                     |
++------------------------------------------------------------------+
+```
+
+Export a Plotly chart to static image formats.
+
+## Usage
+
+```
+/chart-export {format}
+```
+
+## Arguments
+
+- `format` (required): png, svg, or pdf
+
+## Tool Mapping
+
+```python
+chart_export(figure=figure_json, format="png", width=1200, height=800, scale=2)
+```
+
+Requires `kaleido` package: `pip install kaleido`
+
+## Related Commands
+
+- `/chart {type}` - Create a chart
+- `/theme {name}` - Apply theme before export