canbus: reverse-engineer OneControl IDS-CAN bus (read fully mapped, write auth-gated)

Tapped the X180T's CAN bus via CANable 2.0 at the monitor panel's terminator
port. The bus is NOT RV-C — it's Lippert's proprietary IDS-CAN (250k, 11-bit
IDs, (page<<8)|node, 1 Hz broadcasts).

Read side fully mapped from live captures:
- device classes (page-2 type byte: 0x0A tank, 0x1E switched load, 0x21 motor)
- node map for this rig (Catalina 263BHSCK): tanks 27/E2/7D/FE, lights 2A/F8,
  heater 95, pump 61, awning 75 (+ direction & live motor current)
- battery voltage on 29-bit extended frames

Write side: commands are DLC-0 ext frames 0006<node><op>, but auth-gated by a
rolling challenge-response (page 42/43). Replay confirmed dead (spoofed cansend
did not actuate). Not the BLE TEA cypher. response=f(challenge) is deterministic
(no session state) so crackable offline later — seeded 42 pairs in
sniff/2A-auth-pairs.txt.

Includes raw captures (sniff/*.log, force-added past *.log ignore), a read-only
esp32_can ESPHome skeleton, and the log-can.sh sniff helper. Full writeup in
canbus/README.md.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

canbus/sniff/2A-auth-pairs.txt

@@ -0,0 +1,45 @@
+# Lippert IDS-CAN command-auth challenge/response pairs
+# node 2A (exterior lights), captured 2026-06-11, app-driven on/off x~20
+# format: <challenge_hex> <response_hex>  (both 4 bytes, from page42/page43 payload bytes 3-6)
+9577DE9B C033B197
+1ADF97F8 F48604B6
+E09D5B01 44A5C15E
+DEA757A0 04DD9CBA
+8862C15F 29AA626F
+E14DB9AE 25373B94
+23A3ED5D 3250A48A
+F3A3B602 A6E58995
+FC5F3883 47780DAF
+16B2AE10 28FE5A23
+11C34FD9 6A1B9415
+2FFC637D 0A5CE05B
+DB284B0C 052D2687
+FA14432F 71EDD5F4
+B140D087 356CFD45
+20337B7E 81D3136A
+968F0543 F91AB4A3
+28DA207A 781A423E
+AB4040DE 5B652F23
+7A3CA469 48DF5FCF
+AFDFBC25 2E52F019
+B7394203 C62B24EE
+ECA9CD68 361924A5
+83198E6B 7E9DF4D9
+4D3F6429 86793E68
+0804DD8B 953137D5
+E1525A39 1091BB17
+C77CAA9B F9746AAC
+B98C209C 46385C66
+BBE34815 F717E80E
+2DAA8E0C BB1CF451
+D4AAC54D FD806835
+E1ECB36C FE26F014
+BF066519 4F23CAAF
+DA8EF86C ED575807
+0FD2C9B9 6B0EF761
+4B192BC2 0DC60551
+A0421A64 54A5AD6D
+2BE06274 BD49B339
+8FF0B6E5 C18D49F2
+45FE7D5E 0A44BB97
+BAA07C27 54E5C64B