Add a PC renderer for the themed pages; fix overlapping layouts

tools/render_pages.py compiles the page code natively with g++ against
ESPHome's own display and font code and the font bitmaps of the last
`esphome compile`, and draws pages to PNG at chosen moments with sample
data (normal, empty, alert, busy), as a contact sheet, or as one example
per page in docs/images/pages (now shown in the README).

Fixes found with it: Cyber HUD zone names ran into the temperatures,
the breach header label hit the tag and the column marker the matrix
label; KonoSuba subtitle, guild weather icon, cabbage text and all-day
deadline, and hills through the party; Steins;Gate D-mail recipient, the
microwave display, the gadget card value and world line labels; LCARS
room rows, readout bars and data cascade, warp core readouts, and the
captain's log weather wording.

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

components/el512/el512_pages.h

@@ -96,6 +96,12 @@ inline std::string upper(std::string s) {
   return s;
 }
 
+inline std::string lower(std::string s) {
+  for (auto &c : s)
+    c = (char) tolower((unsigned char) c);
+  return s;
+}
+
 inline int text_width(display::Display &it, display::BaseFont *font, const char *text) {
   int x, y, w, h;
   it.get_text_bounds(0, 0, text, font, display::TextAlign::TOP_LEFT, &x, &y, &w, &h);