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.
- Modified the `_generate_sql_from_natural_language` helper function in `routes/sql_explorer.py` to use direct REST API calls via the `requests` library instead of the `google-generativeai` Python library.
- Added `requests` and `json` imports and removed the `google-generativeai` import.
- Updated error handling for API communication and response parsing.
- Updated the corresponding changelog entry.
Here is a conventional commit message summarizing the changes:
```
feat: Refactor SQL Explorer into blueprint
- Moved SQL Explorer routes (view explorer, save/load/execute/delete queries, view schema, plot queries) from `app.py` into a new blueprint at `routes/sql_explorer.py`.
- Added `/sql` URL prefix to the blueprint.
- Registered the new `sql_explorer_bp` blueprint in `app.py`.
- Removed the original SQL Explorer route definitions from `app.py`.
- Updated `url_for` calls in relevant templates (`sql_explorer.html`, `partials/sql_explorer/sql_query.html`, `base.html`) to reference the new blueprint endpoints (e.g., `sql_explorer.sql_explorer`).
- Updated `templates/changelog/changelog.html` to document this refactoring.
```
