Voila rendering, map min_zoom, and analysis chart theming

[dfguerrerom]

Follow-up UI work on the sample-design branch, on top of the (already merged) PR #10.

Three commits:

• Support Voila rendering — runtime-aware tile client URLs so the app renders under Voila.
• Default map min_zoom of 5 — SbaeMap now floors zoom-out at level 5 (roughly continental), overridable via the constructor. SepalMap never set min_zoom, so it previously inherited ipyleaflet's 0.
• Match analysis chart theming to the summary charts — thread the app theme_toggle down to AreaEstimateChart and set a transparent backgroundColor (#1e1e1e00), so it stops showing ECharts' built-in dark-theme #100c2a fill and tracks the theme toggle in lockstep with the summary pie/precision charts.

Tests: 111 passed.

[dfguerrerom]

Superseded — closing. The branch's merge-base is #10, so it predates #13/#14/#16/#17/#18 and merging it would revert ~3,500 lines (analysis dashboard, vector_tiles, PMTiles points, tile bridge, 11 test files).

Of its three commits:

• Chart theming — already in main via Analysis dashboard and PMTiles sample-point rendering #13: backgroundColor="#1e1e1e00" is on all four analysis charts plus summary.py, and theme_toggle is threaded down to them.
• Voila rendering — obsolete both ways. pysepal 3.8.1's runtime_context.get_current_runtime_id() resolves the runtime under Voila/Jupyter, so the NotificationProvider guard would now disable notifications there (verified: ui.ipynb executes clean under a real ipykernel on main). The _tile_client_kwargs_for_runtime half is covered by the comm bridge (Mount tile comm bridge by default so tiles load on SEPAL #16) plus host="127.0.0.1" on the TileClient.
• min_zoom=5 — the only thing still missing; re-landed on top of main in Default map min_zoom of 5 #19.