Add four animated KonoSuba ESPHome pages

Megumin's daily explosion, the Adventurers' Guild quest board (agenda,
weather, solar), Megumin's adventurer card and a party battle against a
giant toad with a live-data battle log. Original 1-bit pixel art lives in
tools/konosuba_sprites.py, which generates konosuba_sprites.h and can
render a preview PNG.

Home data and drawing helpers shared by the themed pages move to
el512_pages.h; the display gains dither_mask() for a dissolve-in intro.

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

README.md

@@ -83,6 +83,8 @@ components/el512/       shared driver + ESPHome component (one copy of the code)
   still_alive.*         Portal end-credits show, 5x7 font (el512_font.h)
   still_alive_data.h    show content, generated by tools/import_still_alive.py
   cyberpunk.*           animated Cyberpunk-style ESPHome pages
+  konosuba.*            animated KonoSuba pages; konosuba_sprites.h from tools/
+  el512_pages.h         home data and helpers shared by the themed pages
   el512_display.*       ESPHome display platform `el512`
   __init__.py, display.py   ESPHome config schema
 lib/EL512/              Arduino library: Adafruit_GFX front end (EL512_GFX)
@@ -90,7 +92,7 @@ src/still_alive/        Portal-style end-credits demo (env still_alive)
 src/test_images/        test sketch: cycles through 12 test images (env esp32dev)
 esphome/                el512-panel.yaml (Home Assistant display), el512-smoke.yaml
 home_assistant/packages/  el512_panel.yaml: helper sensors for the ESPHome pages
-tools/                  import_still_alive.py
+tools/                  import_still_alive.py, konosuba_sprites.py
 test/                   unit tests (placeholder)
 docs/                   datasheet and notes
 ```
@@ -109,9 +111,9 @@ pio device monitor
 ## ESPHome / Home Assistant
 
 [esphome/el512-panel.yaml](esphome/el512-panel.yaml) turns the panel into a Home
-Assistant display with twelve pages: clock and weather, forecast, agenda, a sensor
-dashboard with a message line, now playing, Plex, solar, Still Alive, and four
-animated [Cyberpunk-style pages](#cyberpunk-pages). Pages
+Assistant display with sixteen pages: clock and weather, forecast, agenda, a sensor
+dashboard with a message line, now playing, Plex, solar, Still Alive, and eight
+animated themed pages ([Cyberpunk](#cyberpunk-pages), [KonoSuba](#konosuba-pages)). Pages
 rotate on an interval; Home Assistant gets a page select, a pause switch, the
 interval, a message text, a "Play Still Alive" button, and Display / Low power mode
 switches (ENABLE, _LOWPWR).
@@ -215,6 +217,38 @@ These pages are inspired by the look of Cyberpunk 2077 and use no assets from it
 Cyberpunk 2077 is a trademark of CD PROJEKT S.A.; this project is not affiliated
 with or endorsed by CD PROJEKT RED.
 
+## KonoSuba pages
+
+Four animated pages around the KonoSuba party, drawn by
+[components/el512/konosuba.cpp](components/el512/konosuba.cpp) with Cinzel, Nunito,
+Press Start 2P, Noto Sans JP and Dela Gothic One (Google Fonts), all in the rotation:
+
+- **KonoSuba Explosion**: Megumin chants under a night sky while a magic circle
+  draws itself, then EXPLOSION (flash, shockwave, mushroom cloud, screen shake). She
+  ends up flat on the ground, Kazuma rates the explosion, and the day's count goes up.
+- **KonoSuba Guild**: the Adventurers' Guild board: your next agenda events as quest
+  notes (rank, deadline, reward in Eris, NEW! for today), the weather as a hazard
+  notice and today's solar yield as the cabbage-harvest bounty, while cabbages fly by.
+- **KonoSuba Card**: Megumin's adventurer card: level from today's solar yield, mana
+  from solar power, stamina from what the house load leaves, a daily luck roll, and the
+  explosions cast today.
+- **KonoSuba Battle**: the party against a giant toad in a JRPG window; the battle log
+  uses live values (Kazuma steals the grid import, Megumin's explosion does the solar
+  watts in damage).
+
+The pixel art lives as text in [tools/konosuba_sprites.py](tools/konosuba_sprites.py),
+which writes `components/el512/konosuba_sprites.h`; `--preview sprites.png` renders it
+magnified for checking:
+
+```bash
+python tools/konosuba_sprites.py --preview sprites.png
+```
+
+These pages are fan art: the pixel art and all texts are original, and no material
+from the series is used. KonoSuba (*Kono Subarashii Sekai ni Shukufuku wo!*) is by
+Natsume Akatsuki and Kurone Mishima, © its rights holders; this project is not
+affiliated with or endorsed by them.
+
 ## Using the driver
 
 ```cpp