Fix TUI modal input precedence over Playbook

[edwin-zvs]

Summary

• record the identity of the topmost rendered modal alongside its hit-test bounds
• route Remote Control keyboard and mouse input before a covered rolled-down Playbook
• give Help, Tasks, session picker, and Configure consistent pointer precedence while preserving each modal's established dismissal and reroute semantics
• add rendered-frame unit coverage, a real PTY keyboard/mouse regression, and a focused modal-precedence design spec

Root cause

The layout snapshot stored only one modal rectangle. Keyboard routing checked the focused Playbook before Remote Control, mouse routing called the Playbook editor before consulting the visible dialog, and generic click handling inferred rectangle ownership from whether a Playbook happened to remain mounted. A Remote Control dialog could therefore paint above the Playbook while input still mutated the editor underneath.

Testing

• env -u NO_COLOR cargo test -p construct-cli
• focused rendered-frame modal routing tests for Remote Control, Help, session picker, Configure reroute, and operator-view behavior
• env -u NO_COLOR cargo test -p construct-e2e
• cargo build
• git diff --check

The repository e2e package is named construct-e2e; timing and network dependent tests remain ignored by their existing annotations.