refactor(sql_explorer): Replace Plotly with SVG rendering for plots

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.

templates/changelog/changelog.html

@@ -10,6 +10,23 @@
         <div class="prose max-w-none">
             <p>Updates and changes to the site will be documented here, with the most recent changes listed first.</p>
 
+            <!-- New Entry for SQL Explorer SVG Plots -->
+            <hr class="my-6">
+            <h2 class="text-xl font-semibold mb-2">April 15, 2025</h2>
+            <ul class="list-disc pl-5 space-y-1">
+                <li>Replaced Plotly graph generation in SQL Explorer with direct SVG rendering:</li>
+                <ul class="list-disc pl-5 space-y-1">
+                    <li>Updated `plot_query` and `plot_unsaved_query` endpoints in `routes/sql_explorer.py` to fetch raw
+                        data.</li>
+                    <li>Added `prepare_svg_plot_data` function in `utils.py` to process data and determine plot type
+                        (scatter, line, bar, or table fallback).</li>
+                    <li>Created `templates/partials/sql_explorer/svg_plot.html` template to render SVG plots with axes
+                        and basic tooltips.</li>
+                    <li>Removes the need for Plotly library for SQL Explorer plots, reducing dependencies and
+                        potentially improving load times.</li>
+                </ul>
+            </ul>
+
             <!-- New Entry for Dismissible Exercise Graph -->
             <hr class="my-6">
             <h2 class="text-xl font-semibold mb-2">April 13, 2025</h2>