fix(wayland): handle the wl_keyboard v10 repeated key state instead of aborting

[nikicat]

Problem

wl_keyboard v10 lets the compositor take over key repeat. It signals this by sending repeat_info { rate: 0 } (disabling client-side repeat), then delivers held keys as key { state: repeated } — a third key_state value added in that version.

The Wayland keyboard dispatch matches only Pressed and Released:

WlKeyboardEvent::Key { key, state: WEnum::Value(WlKeyState::Pressed), .. } => { ... }
WlKeyboardEvent::Key { key, state: WEnum::Value(WlKeyState::Released), .. } => { ... }
...
_ => unreachable!(),

so anything else aborts the process. That arm is reachable from compositor-supplied data in two ways — the new Repeated state, and any WEnum::Unknown state — which makes it a panic on untrusted input rather than an invariant.

Impact

main is not affected today: sctk 0.19 caps the wl_seat bind at v7, so no compositor will send repeated. It becomes a hard crash the moment rio-window moves to sctk 0.20, which binds wl_seat up to v10.

I hit it on a fork carrying that bump, on mutter 50.3 (advertises wl_seat v10). Holding any key killed the terminal:

thread 'main' panicked at rio-window/src/platform_impl/linux/wayland/seat/keyboard/mod.rs:305:18:
internal error: entered unreachable code

Fix

• Handle WlKeyState::Repeated as a repeat key press. No repeat-timer bookkeeping is needed: per the protocol the compositor only sends it after repeat_info { rate: 0 }, so client-side repeat is already disabled and the two paths are mutually exclusive.
• Downgrade the remaining catch-all — and its twin on the keymap format — from unreachable!() to warn!, so unknown protocol values degrade instead of aborting.

Verification

Rebuilt with the sctk 0.20 bump on mutter 50.3 and held a key via ydotool with WAYLAND_DEBUG=1:

--- key events (key, state) ---
      2 105 1)
    104 105 2)
RESULT: ALIVE
--- panics: 0 ---

104 state: repeated events delivered, key repeat works, process survives. Before the change the first one aborted. Also cargo check -p rio-window on this branch's base (sctk 0.19) — clean.

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