Implement native InputCapture with private EIS receiver transport

Add consent, zones and outside-edge barriers, connection-scoped leases, bounded input queues and keyboard/pointer forwarding. Restore local input on release, locking, topology or keymap changes, receiver loss and emergency escape. Preserve held-key state and distinguish finger stops from absent scroll axes.

Validation: independent review cleared; 5 native InputCapture unit tests; 32 portal tests; official D-Bus contract checks on a private bus; real installed libei receiver interoperability test. Live physical barrier and consent interaction remain to be checked in a desktop session.

compositor/src/handlers/activation.rs

@@ -27,7 +27,7 @@ impl XdgActivationHandler for Ferese {
         data: XdgActivationTokenData,
         surface: WlSurface,
     ) {
-        if self.session_lock.active {
+        if self.session_lock.active || self.input_capture.captures(1) {
             return;
         }
         let valid = data.serial.is_some() && data.timestamp.elapsed() <= TOKEN_MAX_AGE;