Support every datasheet command and map text to the CG-ROM fonts

- Brightness, blink, screen on/off, annunciators, cursor control, display
  modes, user-defined characters, code table, international charset,
  peripheral select, self-test, raw writes and reinit
- UTF-8 text is encoded with the selected code table (tables generated
  from Python codecs by tools/gen_charmaps.py), falling back to
  accent-stripping
- Settings survive reinit and the self-test
- Example gains brightness select and display switch, and uses the git
  source on mangavalk.com

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

tools/gen_charmaps.py

@@ -0,0 +1,78 @@
+"""Generate components/samsung_vfd/charmaps.h from Python's code page codecs.
+
+Each table lists the Unicode code point shown for bytes 0x80..0xFF in one of
+the display's CG-ROM fonts (datasheet section 6), or 0 where there is none.
+CP10 (for DP86-20) has no standard codec, so it gets no table.
+
+Run from the repo root:  python tools/gen_charmaps.py
+"""
+
+from pathlib import Path
+
+# Same order as the ESC t n argument (datasheet 5.4.18).
+TABLES = [
+    ("PC437", "cp437"),
+    ("PC850", "cp850"),
+    ("PC866", "cp866"),
+    ("PC737", "cp737"),
+    ("PC775", "cp775"),
+    ("CP10", None),
+    ("PC864", "cp864"),
+    ("PC852", "cp852"),
+]
+
+OUT = Path(__file__).resolve().parent.parent / "components" / "samsung_vfd" / "charmaps.h"
+
+
+def high_half(codec):
+    points = []
+    for b in range(0x80, 0x100):
+        try:
+            ch = bytes([b]).decode(codec)
+        except UnicodeDecodeError:
+            ch = ""
+        points.append(ord(ch) if len(ch) == 1 else 0)
+    return points
+
+
+def main():
+    lines = [
+        "// Generated by tools/gen_charmaps.py -- do not edit.",
+        "#pragma once",
+        "",
+        "#include <cstdint>",
+        "",
+        "namespace esphome {",
+        "namespace samsung_vfd {",
+        "",
+    ]
+    names = []
+    for name, codec in TABLES:
+        if codec is None:
+            names.append("nullptr")
+            continue
+        ident = f"CHARMAP_{name}"
+        names.append(ident)
+        pts = high_half(codec)
+        lines.append(f"// {name} ({codec}), bytes 0x80..0xFF")
+        lines.append(f"static const uint16_t {ident}[128] = {{")
+        for i in range(0, 128, 8):
+            row = ", ".join(f"0x{p:04X}" for p in pts[i : i + 8])
+            lines.append(f"    {row},  // 0x{0x80 + i:02X}")
+        lines.append("};")
+        lines.append("")
+    lines.append("// Indexed by CodeTable (the ESC t argument); nullptr = no mapping known.")
+    lines.append(f"static const uint16_t *const CHARMAPS[{len(TABLES)}] = {{")
+    for (name, _), ident in zip(TABLES, names):
+        lines.append(f"    {ident},  // {name}")
+    lines.append("};")
+    lines.append("")
+    lines.append("}  // namespace samsung_vfd")
+    lines.append("}  // namespace esphome")
+    lines.append("")
+    OUT.write_text("\n".join(lines), encoding="utf-8", newline="\n")
+    print(f"wrote {OUT}")
+
+
+if __name__ == "__main__":
+    main()