Implement draggable points on the EQ graph

[jtl5770]

• Add coordinate conversion helpers (y_to_db)
• Implement drag gesture handlers for real-time frequency and gain adjustment
• Account for combined curve response and shelf filter correction during drags
• Batch UI updates for smoother performance
• Connect Gtk.GestureDrag to the graph area

[Copilot]

Pull request overview

Adds interactive drag controls to the EQ graph so users can adjust a band’s frequency/gain by dragging the on-curve point, with coordinate conversion helpers and batched UI/engine updates to keep interaction smooth.

Changes:

• Wire up Gtk.GestureDrag on the graph drawing area to begin/update/end drag interactions.
• Implement drag handlers that pick the nearest visible band point and update band frequency/gain in real time (including shelf correction).
• Add y_to_db() to invert the existing db_to_y() mapping for pointer→dB conversion.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/mini_eq/window_layout.py	Attaches a Gtk.GestureDrag controller to the EQ graph area and connects it to the new handlers.
src/mini_eq/window_graph.py	Implements drag selection + updates, and adds y_to_db() for coordinate conversion.

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[jtl5770]

I've updated the PR with the following changes:

• Fixed Solo State Logic: Calculations for the 'other response' now preserve the full band list and original solo context.
• Unified Coordinates: on_graph_pressed now uses graph_plot_bounds() for consistent coordinate conversion.
• Filter-Aware Vertical Drag: Gain adjustment is now restricted to gain-capable filters (Bell, Shelves).
• Q Adjustment: Added Shift+Vertical drag to adjust the filter Q value. This interaction is isolated from frequency and gain changes.
• Code Hygiene: Fixed linting issues and ensured compliance with project formatting standards.
• Verification: All unit and integration tests (full pytest suite, pipewire-gobject compatibility, and headless runtime smoke) are passing.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

[bhack]

Ok I've just extended the test coverage. let's see the CI