Remove require_button, add debug_logging, default no-match to pass-through, and update tests/UI

[multiplex55]

Motivation

• Simplify mouse gesture settings by removing the legacy require_button field and provide an opt-in debug logging switch for diagnostics.
• Make the no-match behavior clearer and safer by defaulting to pass-through right-click so gestures that don't match won't silently swallow clicks.

Description

• Replace require_button with debug_logging in MouseGestureSettings and default it to false (src/plugins/mouse_gestures.rs).
• Wire debug_logging into runtime config (MouseGestureRuntime::apply) and add debug_logging to MouseGestureConfig so runtime receives the flag (src/plugins/mouse_gestures.rs, src/mouse_gestures/service.rs).
• Replace the println!-style debug dump by emitting tracing::debug! for produced gesture tokens when config.debug_logging is enabled (src/mouse_gestures/service.rs).
• Change the default no-match behavior to PassThroughClick and add a short explanatory note to the settings UIs (src/plugins/mouse_gestures.rs, src/gui/mouse_gesture_settings_dialog.rs).
• Update the plugin settings UI and the standalone settings dialog to expose debug_logging and document the no-match fallback (src/plugins/mouse_gestures.rs, src/gui/mouse_gesture_settings_dialog.rs).
• Update unit tests in tests/mouse_gestures_plugin.rs to validate settings (serialize/deserialize) with the new debug_logging field and to confirm legacy fields like require_button are ignored.

Testing

• Added/modified unit test mouse_gestures_settings_ignore_legacy_fields in tests/mouse_gestures_plugin.rs to assert legacy JSON still deserializes and that debug_logging is handled correctly.
• No automated test suite was executed as part of this change; run cargo test locally or in CI to validate the test suite and runtime behavior.

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Codex Task