Replaces the Plotly-based graph generation in the SQL Explorer with direct SVG rendering within an HTML template, similar to the exercise progress sparklines.
- Modifies `routes/sql_explorer.py` endpoints (`plot_query`, `plot_unsaved_query`) to fetch raw data instead of using pandas/Plotly.
- Adds `utils.prepare_svg_plot_data` to process raw SQL results, determine plot type (scatter, line, bar, table), normalize data, and prepare it for SVG.
- Creates `templates/partials/sql_explorer/svg_plot.html` to render the SVG plot with axes, ticks, labels, and basic tooltips.
- Removes the `generate_plot` function's usage for SQL Explorer and the direct dependency on Plotly for this feature.
