refactor(firmware): per-panel folder layout + parametrized config.h

Reorganizes the tree so adding a new panel is purely additive — drop in a
new src/panels/{vendor}/v{N}/ folder and a new platformio.ini env block,
no surgery to existing files.

Layout:
  src/                              shared across all panels
  src/panels/waveshare73/v1/        V1 driver, version, README
  data/waveshare73-v1/              LittleFS payload at this panel's size

src/config.h still defines the panel-agnostic bits (NVS keys, color
palette, network, sync-fail border) but EPD_WIDTH / EPD_HEIGHT / pin
assignments now come from each env's -D flags. Strict #error guards in
production builds; native tests get the V1 defaults via UNIT_TEST.

build_src_filter per env picks the right driver:
  waveshare73-v1   main + panels/waveshare73/v1/
  test-display     test_display + panels/waveshare73/v1/
  sim-yellow       sim_border + panels/waveshare73/v1/
  sim-red          sim_border + panels/waveshare73/v1/
  native-test      unchanged

When V2 hardware lands, the diff is a new env block, a new
src/panels/waveshare133/v1/epd_driver.cpp, and regenerated screens at
data/waveshare133-v1/. Existing V1 envs stay frozen — re-flashing old
units remains a one-liner.

scripts/gen_screens.py takes --panel to target the correct
data/{panel}/ subfolder; defaults to waveshare73-v1.

29/29 native tests pass. All four hardware envs build clean.

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

platformio.ini

@@ -1,66 +1,86 @@
-[env:esp32dev]
+; pictureFrame firmware build environments.
+;
+; Layout: shared sources at src/ root + panel-specific implementations at
+; src/panels/{vendor}/v{N}/. Each panel/version gets its own [env:...] block
+; that sets dimensions, pins, and panel-id via build_flags, and selects its
+; driver via build_src_filter. New panel = new env block + new
+; src/panels/{vendor}/v{N}/ folder + new data/{vendor}-v{N}/ folder. No
+; surgery to existing envs.
+;
+; Old envs preserved as historical snapshots — re-flashing units in the
+; field stays a one-line `pio run -e <env> --target upload` command.
+
+; ── Production firmware: Waveshare 7.3" Spectra-6 + ESP32 dev breakout ──
+[env:waveshare73-v1]
 platform = espressif32
 board = esp32dev
 framework = arduino
-monitor_speed = 115200
 upload_port = /dev/ttyUSB0
 monitor_port = /dev/ttyUSB0
+monitor_speed = 115200
 board_build.filesystem = littlefs
+data_dir = data/waveshare73-v1
+build_src_filter =
+    +<main.cpp>
+    +<panels/waveshare73/v1/>
+build_flags =
+    -DEPD_WIDTH=800
+    -DEPD_HEIGHT=480
+    -DMAX_PANEL_WIDTH=800
+    -DPIN_SCK=18
+    -DPIN_MOSI=23
+    -DPIN_CS=5
+    -DPIN_DC=17
+    -DPIN_RST=16
+    -DPIN_BUSY=4
+    -DPANEL_ID=\"waveshare-7.3-spectra6\"
 lib_deps =
     ricmoo/QRCode@^0.0.1
 
-; Flash a single image from firmware/data/img.bin — no WiFi, no server needed.
-; 1. pio run -e test-display --target uploadfs   (upload the image)
-; 2. pio run -e test-display --target upload      (upload the sketch)
+; ── Hardware visual test: flash a single image from data/waveshare73-v1/img.bin ──
+; No WiFi, no server.
+;   1. pio run -e test-display --target uploadfs   (upload data/)
+;   2. pio run -e test-display --target upload      (upload sketch)
 [env:test-display]
-platform = espressif32
-board = esp32dev
-framework = arduino
-monitor_speed = 115200
-upload_port = /dev/ttyUSB0
-monitor_port = /dev/ttyUSB0
-board_build.filesystem = littlefs
-build_flags = -DENV_TEST_DISPLAY
-build_src_filter = +<epd.cpp> +<test_display.cpp>
-lib_deps =
-    ricmoo/QRCode@^0.0.1
+extends = env:waveshare73-v1
+build_src_filter =
+    +<test_display.cpp>
+    +<panels/waveshare73/v1/>
+build_flags =
+    ${env:waveshare73-v1.build_flags}
+    -DENV_TEST_DISPLAY
 
+; ── Visual hardware tests for the sync-fail / no-WiFi border ──
+; Reads the cached /img.bin from LittleFS and draws it with a yellow / red
+; border. Sets NVS err_border=1 so the next normal-firmware boot exercises
+; the recovery redraw via 304. Flow:
+;   1. pio run -e sim-yellow --target upload      (see yellow border)
+;   2. pio run -e sim-red    --target upload      (see red border)
+;   3. pio run -e waveshare73-v1 --target upload  (back to normal; verifies 304 recovery)
+[env:sim-yellow]
+extends = env:waveshare73-v1
+build_src_filter =
+    +<sim_border.cpp>
+    +<panels/waveshare73/v1/>
+build_flags =
+    ${env:waveshare73-v1.build_flags}
+    -DSIM_BORDER
+    -DSIM_BORDER_COLOR=COLOR_YELLOW
+
+[env:sim-red]
+extends = env:waveshare73-v1
+build_src_filter =
+    +<sim_border.cpp>
+    +<panels/waveshare73/v1/>
+build_flags =
+    ${env:waveshare73-v1.build_flags}
+    -DSIM_BORDER
+    -DSIM_BORDER_COLOR=COLOR_RED
+
+; ── Native unit tests — no hardware, uses test/mocks/ ──
 [env:native-test]
 platform = native
 lib_deps =
     throwtheswitch/Unity@^2.6
 build_flags = -DUNIT_TEST -std=c++17 -iquote test/mocks -iquote test -Itest/mocks -Itest
 test_build_src = no
-
-; Visual hardware tests for the sync-fail / no-WiFi border. Reads the cached
-; /img.bin from LittleFS and draws it with a yellow / red border. Sets
-; NVS err_border=1 so the next normal-firmware boot exercises the recovery
-; redraw via 304. Flow:
-;   1. pio run -e sim-yellow --target upload  (see yellow border on hardware)
-;   2. pio run -e sim-red    --target upload  (see red border on hardware)
-;   3. pio run -e esp32dev   --target upload  (back to normal; verifies 304 recovery)
-[env:sim-yellow]
-platform = espressif32
-board = esp32dev
-framework = arduino
-monitor_speed = 115200
-upload_port = /dev/ttyUSB0
-monitor_port = /dev/ttyUSB0
-board_build.filesystem = littlefs
-build_flags = -DSIM_BORDER -DSIM_BORDER_COLOR=COLOR_YELLOW
-build_src_filter = +<epd.cpp> +<sim_border.cpp>
-lib_deps =
-    ricmoo/QRCode@^0.0.1
-
-[env:sim-red]
-platform = espressif32
-board = esp32dev
-framework = arduino
-monitor_speed = 115200
-upload_port = /dev/ttyUSB0
-monitor_port = /dev/ttyUSB0
-board_build.filesystem = littlefs
-build_flags = -DSIM_BORDER -DSIM_BORDER_COLOR=COLOR_RED
-build_src_filter = +<epd.cpp> +<sim_border.cpp>
-lib_deps =
-    ricmoo/QRCode@^0.0.1