Add verified Joy-Con 2 USB bridge with native mouse support

Implement the standalone USB protocol probe and Bluetooth-backed right Joy-Con bridge with its own persistent virtual pairing identity. Preserve complete ordered native reports, including opaque motion data, and match the console feature set. Relay built-in vibration cues only after genuine source acknowledgement and expose safe BOOTSEL pairing control. Include native capture diagnostics and focused protocol, packet-lifecycle, and cue regressions. Native mouse operation confirmed on Switch with bridge 0.24; private captures and firmware backups remain outside the commit.

tools/switch2_usb_probe/controller_input.h

@@ -0,0 +1,67 @@
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct {
+    bool active;
+    uint32_t serial;
+    uint8_t buttons[2];
+    uint8_t stick[3];
+    // Latest opaque native 08 byte 8.
+    uint8_t native_status;
+    // Cumulative signed relative totals within mouse_epoch, not per-poll
+    // deltas. Cached polls repeat these totals without consuming motion.
+    // Epoch changes on reconnect, including a teardown missed between polls.
+    uint32_t mouse_epoch;
+    int64_t mouse_total_x;
+    int64_t mouse_total_y;
+    // Latest opaque native 08 byte 13.
+    uint8_t mouse_surface;
+} probe_controller_input;
+
+// Core 0, before stdio/peripheral initialization.
+void probe_controller_input_clock_init(void);
+// Core 0, after stdio and before protocol reset or USB startup.
+void probe_controller_input_init(void);
+// True means both cores are registered for flash coordination, not that the
+// radio is ready or a controller is connected. Failure is latched: keep USB
+// and flash-writing protocol operations disabled rather than retrying startup.
+bool probe_controller_input_start(void);
+// Core 0 after start(): polls the existing two-second BOOTSEL hold gesture.
+// True means a Bluetooth pairing-window request was queued. Long holds NEVER
+// clear pairings in this bridge, and this does not inject USB controller input.
+bool probe_controller_input_pairing_task(void);
+// Core 0 native 08 relay: disabled until explicitly enabled after flash-ready
+// startup. Disable clears queued data, repeated enable preserves it. Resets
+// must disable the stream; this never changes Bluetooth bonds or pairing.
+// Only subsequent selected-source packets enter the separate 32-entry FIFO.
+// Overflow drops queued history and retains only the arriving packet.
+void probe_controller_input_set_native_stream(bool enabled);
+// Copy a full opaque 63-byte payload (without report ID), oldest first. Returns
+// its never-reused boot-lifetime serial; 0 leaves report untouched. Latest source
+// or head >=500 ms old discards the FIFO; now_ms is the Pico boot-ms clock.
+// Nondestructive until successful HID submission followed by commit.
+uint32_t probe_controller_input_peek_native_report(uint32_t now_ms, uint8_t report[63]);
+// Remove only the exact current head once. A stale/replaced token cannot pop a
+// new stream's packet. Before flash-ready startup peek/commit return 0/false.
+bool probe_controller_input_commit_native_report(uint32_t serial);
+// Built-in vibration samples only; raw HD-rumble output is not forwarded.
+// A nonzero token means queued, not acknowledged. Result: 0 pending, 1 real
+// source ACK, -1 failed/stale. Reset cancels the request, never stored pairing.
+bool probe_controller_input_play_sample(uint8_t sample_id, uint64_t* token);
+int probe_controller_input_sample_result(uint64_t token, uint32_t now_ms);
+void probe_controller_input_cancel_sample(void);
+// Core 0 at 250 Hz; now_ms uses the Pico boot-millisecond clock. Only fresh
+// native 08 buttons/stick and cumulative mouse totals are exposed. Inactive
+// fields are zero except serial; the USB protocol must supply its calibrated
+// stick center rather than forwarding inactive stick bytes.
+void probe_controller_input_poll(uint32_t now_ms, probe_controller_input* out);
+
+#ifdef __cplusplus
+}
+#endif