Remote: match the old remote's hardware; old remote code in LEGACY

- LEGACY/remote/teensy/: old remote sketch from
  https://mangavalk.com/Hexapod/remote.git @ 492dece (reference only).
- remote/Config.h: sticks on A0-A5, Nextion on Serial1 (0/1), as in the
  old sketch; MPU6050 moved to Wire2 (25/24) since A4/A5 are Wire's pins.
- NextionUI: controls on a vscope-global "control" page added to the
  old HMI; keeps the old t1 status texts; the old page-1 b2 button (and
  serial 'U') enter Nextion upload passthrough, following the PC's baud.
- Docs: NEXTION.md, remote README wiring, CLAUDE.md.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2026-current/remote/Config.h

@@ -14,7 +14,7 @@
 constexpr float TX_HZ = 100.0f;
 
 // ---- Radio (nRF24L01) on SPI0: MOSI 11, MISO 12, SCK 13 ----
-// BENCH: placeholder CE/CSN pins - match your wiring.
+// CE/CSN as in the old remote sketch (LEGACY/remote/teensy/Nrf.h).
 constexpr uint8_t RADIO_CE_PIN  = 9;
 constexpr uint8_t RADIO_CSN_PIN = 10;
 // Auto-retransmit: (delay units of 250us, count). Kept short on purpose - a
@@ -31,9 +31,11 @@ constexpr uint32_t LINK_LOST_MS = 300;
 // Logical axis order used everywhere in the remote code.
 enum StickAxis : uint8_t { L_X = 0, L_Y, L_TWIST, R_X, R_Y, R_TWIST, NUM_AXES };
 
-// BENCH: placeholder pins. A4/A5 (18/19) are skipped because they're the I2C
-// pins the MPU6050 uses.
-constexpr uint8_t STICK_PINS[NUM_AXES] = { A0, A1, A2, A3, A6, A7 };
+// A0-A5 in a row, as wired for the old remote (LEGACY/remote/teensy/Joysticks.h).
+// A4/A5 are also Wire's SDA/SCL - that's why the MPU6050 is on Wire2 below.
+// BENCH: which physical axis is on which pin wasn't recoverable from the old
+// code; reorder these so each lands on the right logical axis ('p' dump).
+constexpr uint8_t STICK_PINS[NUM_AXES] = { A0, A1, A2, A3, A4, A5 };
 
 // Each logical axis must end up: X + = pushed RIGHT, Y + = pushed FORWARD
 // (away from you), TWIST + = rotated COUNTERCLOCKWISE seen from above.
@@ -67,7 +69,9 @@ constexpr float STICK_EXPO[NUM_AXES]     = { 0.25f, 0.25f, 0.30f, 0.20f, 0.20f,
 // One-pole low-pass on raw ADC counts (1 = no filtering). Pots are noisy.
 constexpr float STICK_FILTER_ALPHA = 0.5f;
 
-// ---- Remote IMU: MPU6050 on I2C (Wire: SDA 18, SCL 19) ----
+// ---- Remote IMU: MPU6050 on the second I2C bus (Wire2: SDA2 = 25, SCL2 = 24) ----
+// Not Wire (18/19): those pins are stick axes A4/A5.
+#define IMU_WIRE Wire2
 constexpr uint8_t IMU_ADDR = 0x68;   // 0x69 if AD0 is pulled high
 // Mounting remap: which chip axis (0=X,1=Y,2=Z) and sign gives each handset
 // axis. Handset frame: +X = away from you, +Y = your left, +Z = up.
@@ -103,11 +107,24 @@ constexpr uint32_t WALK_LINGER_MS = 250;
 // (post-deadzone, -1000..1000 scale), so the robot never arms mid-command.
 constexpr int16_t ARM_CENTER_TOLERANCE = 50;
 
-// ---- Nextion touchscreen on Serial2 (RX2 = pin 7, TX2 = pin 8) ----
-#define NEXTION_SERIAL Serial2
-// BENCH: Nextion ships at 9600. The HMI's Program.s must set `bauds=115200`
-// (see remote/NEXTION.md) or change this to match.
+// ---- Nextion touchscreen on Serial1 (RX1 = pin 0, TX1 = pin 1), as in the old remote ----
+#define NEXTION_SERIAL Serial1
+// BENCH: the old sketch used the ITEAD library, whose nexInit() talks at 9600
+// unless it was modified. This firmware expects 115200: add `bauds=115200`
+// to the HMI's Program.s (see remote/NEXTION.md) or set 9600 here.
 constexpr uint32_t NEXTION_BAUD             = 115200;
+// Controls live on this page (remote/NEXTION.md). Its components must have
+// vscope = global, so the firmware can update them whichever page is showing.
+#define NEXTION_CONTROL_PAGE "control"
+// The old HMI's link-status texts (pages 1 and 3, both named t1), also
+// vscope = global. BENCH: use your real page names (Nextion's default
+// names are page0..page5; only page 4 "uploadscreen" is known).
+constexpr const char* NEXTION_STATUS_TEXTS[] = { "page1.t1", "page3.t1" };
+// The old HMI's "upload" button: page 1, component id 5 (b2), sends the
+// standard touch event. It puts the remote into Nextion upload passthrough.
+constexpr uint8_t NEXTION_UPLOAD_BUTTON_PAGE = 1;
+constexpr uint8_t NEXTION_UPLOAD_BUTTON_ID   = 5;
+#define NEXTION_UPLOAD_PAGE "uploadscreen"
 constexpr uint32_t NEXTION_FULL_REFRESH_MS  = 2000;   // re-push everything periodically (self-heals after a display reset)
 constexpr uint32_t NEXTION_LINK_REFRESH_MS  = 250;    // link-quality text update rate
 constexpr uint32_t STATUS_MESSAGE_MS        = 2500;   // how long transient status messages stay up