Fix SpanSelector interactive mode forcing axes limits to include 0

[Copilot]

The SpanSelector widget was incorrectly expanding axes limits to include 0 when created with interactive=True, even when the plotted data didn't include 0. This regression affected the expected behavior where axes limits should remain focused on the actual data range.

Problem

When creating a SpanSelector with interactive=True:

from matplotlib import pyplot as plt
from matplotlib.widgets import SpanSelector

fig, ax = plt.subplots()
ax.plot([10, 20], [10, 20])  # Data range: 10-20
ss = SpanSelector(ax, print, "horizontal", interactive=True)
print(ax.get_xlim())  # Expected: ~(10, 20), Actual: ~(0, 20)

The axes xlimits were being expanded to include x=0, which was not the case in Matplotlib 3.4 with the old span_stays parameter.

Root Cause

When interactive=True, SpanSelector creates interactive handles via ToolLineHandles at initialization. These handles were positioned using self.extents, which returns (0, 0) from the initially created Rectangle at origin. This caused axvline(0) calls that forced the axes to include x=0, even though the handles were invisible.

Solution

Modified _setup_edge_handle to use current axes limits (ax.get_xlim() or ax.get_ylim()) as initial handle positions instead of self.extents. This prevents unwanted axes expansion while maintaining all interactive functionality.

The key change ensures handles are created within existing axes bounds:

# Before: uses (0, 0) positions
self._edge_handles = ToolLineHandles(self.ax, self.extents, ...)

# After: uses existing axes limits  
if self.direction == 'horizontal':
    initial_positions = self.ax.get_xlim()
else:
    initial_positions = self.ax.get_ylim()
self._edge_handles = ToolLineHandles(self.ax, initial_positions, ...)

After user interaction, handles are updated to correct positions via the normal extents.setter mechanism, preserving all existing behavior.

Fixes #1.

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[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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