feat(recolor): collapsible, drag-reorderable pane sections

[grymmjack]

What

The Recolor pane below the preview is now eight uniform, collapsible, drag-reorderable sections, and the arrangement persists.

Section	Contents	New?
Palette · N colors	the swatch grid	now collapsible
Cleaning	Extract pixels from JPEG · Remove JPEG artifacts · Undither	new section
Resize	upscaler + downsample factors	was collapsible
Adjustments	the reorderable op stack	was collapsible
Pixelate	mosaic block size	was collapsible
Color balance	per-channel R/G/B offset	was collapsible
Post FX	scanlines / glow / vignette / phosphor	was collapsible
Recolor	Original · Reduce · palette chooser · dither · textmode export	now collapsible

• ⊞ All / ⊟ All in the pane header collapses or expands everything. Right-click it to restore the default section order. ⟲ Reset all still clears settings, never the layout.
• Drag a section's grip to reorder; the insertion line targets whole sections (header + body), mirroring the Adjustments row drag.
• Headers carry an activity marker so a collapsed section still says whether it's doing something — Resize * · 320×200, Cleaning * · 2 on, Recolor * · ANSI32.
• The whole header row is the toggle, not just the words, with a hover highlight.
• Preview + the Export/Save row stay outside the sections, directly under the thumbnail, so 💾 Save recolored / Export .GPL… / Export textmode remain reachable on a small screen whatever is collapsed.

How

• New RecolorSection enum + the free fn recolor_section (drag grip + CollapsingState header + indented body). ui_recolor's tail is now a for loop over self.recolor_order with a match dispatching to one ui_sec_* method per section.
• The open state is ours, not egui's — a [bool; COUNT] indexed by discriminant. It has to be: persist_egui_memory() returns false, so egui's collapsing state dies at exit, and "collapse all" has to be forceable. Note that forcing CollapsingHeader::open means the header's own clicked() stops toggling, which is why the title is a click-sensed target that calls state.toggle itself.
• Persistence: recolor_sections (a Vec<u8> of discriminants) + recolor_open (a Vec<bool>), restored by the pure recolor_order_from / recolor_open_from. Variants are appended, never reordered or removed: an unknown id is dropped and a section missing from a saved order is appended, so a config written before a section existed gains it at the end rather than losing it.
• Mechanically this splits ui_recolor's ~2300-line body into per-section methods; the bodies are moved verbatim (hence the large diff — it's mostly code motion + re-indentation).

Testing

• cargo test — 505 passed, 0 failed (3 new: section id stability, order round-trip/repair, open-state defaults filling a short record).
• cargo clippy clean; cargo fmt applied to src/app.rs only.
• Added shoot_recolor_sections behind the existing gui-screenshots feature, rendering the pane collapsed / expanded / reordered headlessly (lavapipe). Verified visually: all eight sections collapse to one row each, Cleaning groups the three checkboxes, reordering renders in the new order, and the header row still fits Bypass at dock width.

Notes

• The stale cargo test counts in CLAUDE.md (391 / 266) were already wrong before this change; left alone rather than folded into this diff.

---

Generated by Claude Code