fix(ui/tree): no fingerer-ring bleed at the bottom of the modal

[flipbit03]

Summary

The tree modal hardcoded HELP_BAR_HEIGHT = 2 and shrunk its own rect to area.height - 2, but the help bar actually uses wrapped_height(help_text, …) which is 1 on wide-enough terminals where the help text fits in a single row. When that happens, the modal stops 2 rows from the bottom but the help bar only paints the last 1 — leaving a one-row strip where the biscuit + orbiting fingerers underneath show through.

Fix: pass the live help_height from ui::mod.rs into tree::draw so the modal hugs exactly the row above the actual help bar. The hardcoded constant goes away.

Reproduction (pre-fix)

Run at a wide terminal (≥ ~145 columns wide) where the help text fits on one line, with many owned fingerers so the orbital ring extends to the bottom of the play area. Open the tree (t). The bottom row of the orbit (Index Finger >>, Whole Hand [], Latex Glove <> glyphs etc.) is visible just above the help bar.

Test plan

• Open tree at 220x40 with ~40 owned of every tier — no fingerer glyphs visible between the info pane and the help bar.
• Open tree at 160x50 (narrower, help wraps to 2 rows) — no regression, same coverage as before.
• All previous tests still pass: cargo test, cargo clippy --all-targets -- -D warnings, cargo fmt --check.