feat(13e6): bring up Waveshare 13.3" Spectra-6 end-to-end

Adds a second panel target alongside the 7.3":
- src/panels/waveshare13e6/v1/ — full epd.h impl with hardware SPI on
  FSPI, dual-CS dispatch (CS_M/CS_S split halves), PSRAM framebuffer
  for image/QR/setup-screen render paths
- src/test_display_13e6.cpp + [env:test-display-13e6] — self-contained
  first-pixels color-bar smoke test, kept as a hardware diagnostic
- [env:waveshare13e6-v1] — production env: ESP32-S3-WROOM-2 N32R16V
  with OPI flash + OPI PSRAM (the WROOM-2 is octal flash; QIO mode
  crashes at do_core_init startup.c:328)
- scripts/gen_screens_13e6.py + data/waveshare13e6-v1/ — 1200x1600
  portrait setup screens with QR overlay regions matching the driver
- scripts/data_dir.py — extra_scripts shim that routes uploadfs to the
  right data/ tree based on $PIOENV (PlatformIO ignores per-env data_dir)
- src/epd.h: epd_setup_pins() abstraction so each panel driver owns its
  own pinMode + SPI.begin; main/test_display/sim_border lose all
  panel-specific GPIO and call epd_setup_pins() once at boot
- src/operation.h: report PANEL_ID via X-Panel-Id header on every poll
  so the server can auto-correct Device.model

7.3" production env stays byte-identical, all 43 native tests pass.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

platformio.ini

@@ -10,12 +10,13 @@
 ; Old envs preserved as historical snapshots — re-flashing units in the
 ; field stays a one-line `pio run -e <env> --target upload` command.
 
-; data_dir lives at project level (PlatformIO ignores it inside [env:…]
-; blocks — the silent ignore once led to a LittleFS upload that put every
-; file under /waveshare73-v1/ instead of /, blanking the panel to the
-; epd_fill yellow fallback). All current envs target the V1 panel; when
-; a second panel ships, swap this via an extra_scripts shim that picks
-; the dir from $PIOENV before uploadfs runs.
+; data_dir is single project-wide in [platformio]; PlatformIO silently
+; ignores it inside [env:…] blocks. To route uploadfs to the right
+; LittleFS payload per panel (waveshare73-v1 vs waveshare13e6-v1), each
+; env wires in scripts/data_dir.py via extra_scripts, which overrides
+; PROJECT_DATA_DIR from $PIOENV before SCons evaluates uploadfs.
+; The project-level default below keeps tooling that runs outside a
+; specific env (e.g. raw `pio run`) pointed at the 7.3" payload.
 [platformio]
 data_dir = data/waveshare73-v1
 
@@ -28,6 +29,7 @@ upload_port = /dev/ttyUSB0
 monitor_port = /dev/ttyUSB0
 monitor_speed = 115200
 board_build.filesystem = littlefs
+extra_scripts = pre:scripts/data_dir.py
 build_src_filter =
     +<main.cpp>
     +<panels/waveshare73/v1/>
@@ -85,6 +87,62 @@ build_flags =
     -DSIM_BORDER
     -DSIM_BORDER_COLOR=COLOR_RED
 
+; ── Production firmware: Waveshare 13.3" Spectra-6 + ESP32-S3-ePaper-13.3E6 ──
+; All-in-one board: ESP32-S3-WROOM-2-N32R16V (32MB OPI flash, 16MB OPI PSRAM),
+; CH343 USB-serial on USB-C. PIN_CS aliases CS_M only to satisfy config.h's
+; required-pin check — the driver uses CS_M / CS_S explicitly, never PIN_CS.
+[env:waveshare13e6-v1]
+platform = espressif32
+board = esp32-s3-devkitc-1
+framework = arduino
+monitor_speed = 115200
+board_build.flash_size = 32MB
+board_build.flash_mode = opi
+board_upload.flash_size = 32MB
+board_build.arduino.memory_type = opi_opi
+board_build.filesystem = littlefs
+extra_scripts = pre:scripts/data_dir.py
+build_src_filter =
+    +<main.cpp>
+    +<panels/waveshare13e6/v1/>
+build_flags =
+    -DEPD_WIDTH=1200
+    -DEPD_HEIGHT=1600
+    -DMAX_PANEL_WIDTH=1200
+    -DPIN_SCK=9
+    -DPIN_MOSI=46
+    -DPIN_CS=10
+    -DPIN_CS_M=10
+    -DPIN_CS_S=3
+    -DPIN_DC=11
+    -DPIN_RST=2
+    -DPIN_BUSY=12
+    -DPIN_PWR=1
+    -DPANEL_ID=\"waveshare-13.3-spectra6\"
+    -DBOARD_HAS_PSRAM
+lib_deps =
+    ricmoo/QRCode@^0.0.1
+
+; ── First-pixels smoke test for ESP32-S3-ePaper-13.3E6 ──
+; Self-contained color-bar bringup, no LittleFS / no shared driver. Kept
+; alongside the production env as a fallback for hardware diagnostics:
+; if waveshare13e6-v1 misbehaves, this verifies the panel + SPI bus alone.
+;   pio run -e test-display-13e6 --target upload
+[env:test-display-13e6]
+platform = espressif32
+board = esp32-s3-devkitc-1
+framework = arduino
+monitor_speed = 115200
+board_build.flash_size = 32MB
+board_build.flash_mode = opi
+board_upload.flash_size = 32MB
+board_build.arduino.memory_type = opi_opi
+build_src_filter =
+    +<test_display_13e6.cpp>
+build_flags =
+    -DENV_TEST_DISPLAY_13E6
+    -DBOARD_HAS_PSRAM
+
 ; ── Native unit tests — no hardware, uses test/mocks/ ──
 [env:native-test]
 platform = native