fix(web): accept every panel size and row address type the rgbmatrix library does

The Display form capped columns at 128 and chain length at 24, and its
submit handler (fixInvalidNumberInputs) rewrote anything larger to the cap,
so wide panels and long chains silently saved as the wrong size. The config
API checked none of the hardware numbers, so values the library rejects (odd
rows, parallel 4, PWM dither bits 3) saved and the matrix then refused to
start.

- Form limits now match the pinned library: rows even 8-64, cols >= 16 and
  chain_length >= 1 with no upper bound, parallel 1-3, PWM dither bits 0-2,
  PWM LSB nanoseconds 50-3000.
- save_main_config rejects out-of-range rows, cols, chain_length, parallel,
  brightness, scan_mode, pwm_bits, pwm_dither_bits, pwm_lsb_nanoseconds and
  gpio_slowdown with a 400.
- A stored gpio_slowdown or pwm_dither_bits of 0 renders as 0 instead of the
  default, so saving the tab no longer overwrites it.
- Row Address Type offers 5 (SM5368 / B707 row shift register). Verified on a
  Waveshare 96x48 V2 (24S-A1) on a Pi 4 with the Adafruit Triple LED Matrix
  Bonnet: rows 48, cols 96, row address type 5, BGR, GPIO slowdown 8.
- Help text and docs: FM6124-family panels use Panel Type Standard; on a Pi 5
  the library supports only row address types 0 and 2.

No change to the rpi-rgb-led-matrix submodule.

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

CHANGELOG.md

@@ -47,6 +47,20 @@ Web interface:
   JSON API saves are unaffected. Lets plugins keep deprecated or internal keys
   declared, e.g. countdown's row `id` and weather's `api_key` / `radar_zoom`.
   See `docs/widget-guide.md`.
+- Display settings accept every panel size and timing value the rgbmatrix
+  library does. Saving no longer silently cuts columns to 128, chain length to
+  24 or PWM LSB nanoseconds to 500; rows are held to the library's even 8–64,
+  parallel to 1–3 and PWM dither bits to 0–2. A stored GPIO slowdown or PWM
+  dither bits of 0 no longer shows (and re-saves) as 3 or 1. The config API
+  rejects out-of-range `rows`, `cols`, `chain_length`, `parallel`,
+  `brightness`, `scan_mode`, `pwm_bits`, `pwm_dither_bits`,
+  `pwm_lsb_nanoseconds` and `gpio_slowdown` with a 400 instead of saving a
+  config the matrix refuses to start with.
+- Row Address Type offers 5, the SM5368 / B707 row shift register. The
+  Waveshare 96x48 V2 panel (back silkscreen `24S-A1`) needs it with RGB
+  sequence BGR and, on a Pi 4, a GPIO slowdown of 6–8. Panels with FM6124
+  column drivers need no Panel Type. On a Pi 5 the library supports only row
+  address types 0 and 2.
 
 ## 3.4.0