✨ New Features & 🐛 Bug Fixes

🏷 Data labels — per-entity opt-in (FR #203)

Print the numeric value of every visible data point right above its bar / line / point. Works for both line and bar entities in timeline mode. Labels follow your existing decimal and number-format settings and render in the entity colour with a card-background halo so they stay readable over busy charts. For bars, the font size adapts automatically to the bar width and falls back gracefully when bars get too narrow.

Enable per entity:

entities:
  - entity: sensor.solar_production
    show_data_labels: true
    # optional override:
    # data_labels_font_size: 12

Best paired with reasonable point counts — dense charts will produce
overlapping labels.

📌 Sticky Y-axis in horizontal scroll mode (#205)

When max_visible_interval makes the chart horizontally scrollable, the Y axis (and Y2 if present) now stays pinned to the left edge of the visible area instead of scrolling out with the data. Same behaviour you'd expect from a spreadsheet's frozen first column. Applies to timeline mode; pure state-timeline charts don't have a Y axis and aren't affected.

No configuration needed — it just works in any existing scroll setup.

Several Bug Fixes

#179
#188
#198
#200
#202
#205
#206
#207