refactor: restructure to standard Go project layout (cmd/ + internal/)

- Move entry point to cmd/streamdeck-lets-go/
- Split package main into internal packages:
  - internal/deck: hardware control (Deck, events, brightness)
  - internal/render: key rendering, icons, fonts, PageManager
  - internal/web: HTTP API + embedded SPA
  - internal/daemon: event loop, autoswitch, screensaver, actions
- Add ConfigDir() to internal/config
- Export cross-package API (Deck, PageManager, WebServer, etc.)
- Move dist/arch/ → packaging/ with updated PKGBUILD/.SRCINFO
- Add Makefile (build, test, vet, fmt, install)
- Update README with new build commands and project structure
- Delete unused media.go stub

internal/render/fontawesome_data.go

@@ -0,0 +1,71 @@
+package render
+
+import (
+	"embed"
+	"unicode"
+	"unicode/utf8"
+)
+
+//go:embed assets/Font_Awesome_7_BrandsRegular400.otf
+//go:embed assets/Font_Awesome_7_FreeRegular400.otf
+//go:embed assets/Font_Awesome_7_FreeSolid900.otf
+var faFonts embed.FS
+
+type faStyle int
+
+const (
+	faSolid faStyle = iota
+	faRegular
+	faBrands
+)
+
+func (s faStyle) otfPath() string {
+	switch s {
+	case faSolid:
+		return "assets/Font_Awesome_7_FreeSolid900.otf"
+	case faRegular:
+		return "assets/Font_Awesome_7_FreeRegular400.otf"
+	case faBrands:
+		return "assets/Font_Awesome_7_BrandsRegular400.otf"
+	default:
+		return "assets/Font_Awesome_7_FreeSolid900.otf"
+	}
+}
+
+var faCodepoints map[faStyle]map[string]rune
+
+func init() {
+	faCodepoints = make(map[faStyle]map[string]rune)
+	faCodepoints[faSolid] = buildFAMap(fa7Icons)
+	faCodepoints[faRegular] = buildFAMap(fa7Icons)
+	faCodepoints[faBrands] = buildFAMap(fa7BrandsIcons)
+}
+
+func buildFAMap(src map[string]string) map[string]rune {
+	m := make(map[string]rune, len(src))
+	for name, cp := range src {
+		r, _ := utf8.DecodeRuneInString(cp)
+		camel := camelToKebab(name)
+		m[name] = r
+		m[camel] = r
+		if lower := toLower(name); lower != name {
+			m[lower] = r
+		}
+	}
+	return m
+}
+
+func camelToKebab(s string) string {
+	var out []byte
+	for i, r := range s {
+		if unicode.IsUpper(r) && i > 0 {
+			out = append(out, '-')
+		}
+		out = append(out, byte(unicode.ToLower(r)))
+	}
+	return string(out)
+}
+
+func toLower(s string) string {
+	return string(unicode.ToLower(rune(s[0]))) + s[1:]
+}