TUI rename dialog: tree rows under the dialog show stale tinting after dialog closes

[JDonaghy]

Symptom

After opening + closing the rename dialog (or while it's open) over the file explorer in TUI, the rows under where the dialog was painted retain a faint grey tint background — different from both the regular tree row bg and the selected-row bg. See screenshot from #223 Dialog pilot smoke test:

• `mod.rs` row: has a slight grey bg (this was the rename target).
• `panels.rs` row: has a slight grey bg (this is the active tab's file).

Looks like the dialog's row backgrounds (or its surrounding chrome) leave residue cells that the tree's repaint doesn't fully overwrite.

Likely cause

Either:

1. `Dialog` rasteriser writes more cells than `layout.bounds` claims (so the tree's redraw inside its area doesn't cover the leftover region).
2. Or the tree rasteriser doesn't repaint the full row — only the parts that changed — leaving the dialog's old fill visible.

Most likely #2: `quadraui::tui::draw_tree` fills each visible row with `row_bg`, but after the dialog had been on top, ratatui's diff algorithm may decide some cells are already correct and skip the redraw, leaving stale dialog fg/bg.

Files

• `quadraui/src/tui/tree.rs` — verify per-row background fill always paints (no skip when bg matches the previous frame's primary cell).
• `quadraui/src/tui/dialog.rs` — verify the dialog only paints inside `layout.bounds` (no spillover).

Surfaced by

#223 Dialog pilot smoke test (Session 332).