Support HVP cursor positioning

[rezigned]

Support HVP cursor positioning

Summary

• Handle CSI Ps ; Ps f (HVP) as an alias of CSI Ps ; Ps H (CUP).
• Preserve the existing one-based row and column defaults through canonicalize_params_2.
• Add regression coverage for explicit HVP coordinates and the default home position.

Problem

HVP is the ANSI horizontal and vertical position command. It has the same cursor-positioning behavior as CUP, but the parser only dispatched the H final byte. Applications that use f for absolute cursor movement therefore had their cursor commands ignored.

This is visible with btop, which uses HVP throughout its redraw output. Ignoring those commands causes drawing payloads to be written sequentially and wrap across rows instead of appearing at their requested coordinates.

Fix

Dispatch both final bytes to the existing CUP implementation:

'H' | 'f' => {
    self.screen.cup(canonicalize_params_2(params, 1, 1))
}

No new screen behavior or parser state is introduced.

Verification

cargo fmt --check
cargo test --test csi horizontal_vertical_position
cargo test

Results:

• Focused HVP regression: 1 passed
• Full vt100 suite: 71 passed, 4 ignored
• Downstream upmd suite using the pinned fork revision: 159 passed, 1 ignored
• Manual downstream check: btop renders at the correct cursor coordinates