Sync theme registries and support webterm-theme key in landing YAML

Two issues prevented themes from being applied:

1. Three server-side themes (miasma, github, gotham) were missing from
   the frontend THEMES map in terminal.ts, causing the browser to
   silently ignore them when set via data-theme attribute.

2. Landing YAML only recognized the 'theme' key, but users writing
   'webterm-theme' (matching the Docker label convention) got no theme.
   Now LoadLandingYAML accepts both 'theme' and 'webterm-theme' keys.

All 16 themes are now consistent across ThemeBackgrounds, ThemePalettes,
and the frontend THEMES map.

webterm/config.go

@@ -61,7 +61,7 @@ func LoadLandingYAML(manifestPath string) ([]App, error) {
 			Path:     path,
 			Color:    asString(entry["color"]),
 			Terminal: terminal,
-			Theme:    asString(entry["theme"]),
+			Theme:    firstNonEmpty(asString(entry["theme"]), asString(entry["webterm-theme"])),
 		})
 	}
 	return apps, nil
@@ -144,3 +144,12 @@ func asString(value any) string {
 	}
 	return ""
 }
+
+func firstNonEmpty(values ...string) string {
+	for _, v := range values {
+		if v != "" {
+			return v
+		}
+	}
+	return ""
+}

webterm/config_test.go

@@ -30,6 +30,35 @@ func TestLoadLandingYAML(t *testing.T) {
 	}
 }
 
+func TestLoadLandingYAMLWebtermThemeKey(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "landing.yaml")
+	content := `
+- name: Pro
+  command: /bin/sh
+  webterm-theme: monokai-pro
+- name: Classic
+  command: /bin/sh
+  theme: dracula
+`
+	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	apps, err := LoadLandingYAML(path)
+	if err != nil {
+		t.Fatalf("LoadLandingYAML() error = %v", err)
+	}
+	if len(apps) != 2 {
+		t.Fatalf("expected 2 apps, got %d", len(apps))
+	}
+	if apps[0].Theme != "monokai-pro" {
+		t.Fatalf("expected monokai-pro from webterm-theme key, got %q", apps[0].Theme)
+	}
+	if apps[1].Theme != "dracula" {
+		t.Fatalf("expected dracula from theme key, got %q", apps[1].Theme)
+	}
+}
+
 func TestLoadComposeManifestReadsLabels(t *testing.T) {
 	dir := t.TempDir()
 	path := filepath.Join(dir, "compose.yaml")

webterm/static/js/terminal.ts

@@ -352,6 +352,81 @@ const THEMES: Record<string, ITheme> = {
     brightCyan: "#7dcfff",
     brightWhite: "#c0caf5",
   },
+  // Miasma - earthy warm tones
+  miasma: {
+    background: "#222222",
+    foreground: "#c2c2b0",
+    cursor: "#c2c2b0",
+    cursorAccent: "#222222",
+    selectionBackground: "#c2c2b0",
+    selectionForeground: "#222222",
+    black: "#000000",
+    red: "#685742",
+    green: "#5f875f",
+    yellow: "#b36d43",
+    blue: "#78824b",
+    magenta: "#bb7744",
+    cyan: "#c9a554",
+    white: "#d7c483",
+    brightBlack: "#666666",
+    brightRed: "#685742",
+    brightGreen: "#5f875f",
+    brightYellow: "#b36d43",
+    brightBlue: "#78824b",
+    brightMagenta: "#bb7744",
+    brightCyan: "#c9a554",
+    brightWhite: "#d7c483",
+  },
+  // GitHub Dark Dimmed
+  github: {
+    background: "#1c2128",
+    foreground: "#adbac7",
+    cursor: "#adbac7",
+    cursorAccent: "#1c2128",
+    selectionBackground: "#adbac7",
+    selectionForeground: "#1c2128",
+    black: "#545d68",
+    red: "#f47067",
+    green: "#57ab5a",
+    yellow: "#c69026",
+    blue: "#539bf5",
+    magenta: "#b083f0",
+    cyan: "#39c5cf",
+    white: "#909dab",
+    brightBlack: "#636e7b",
+    brightRed: "#ff938a",
+    brightGreen: "#6bc46d",
+    brightYellow: "#daaa3f",
+    brightBlue: "#6cb6ff",
+    brightMagenta: "#dcbdfb",
+    brightCyan: "#56d4dd",
+    brightWhite: "#cdd9e5",
+  },
+  // Gotham - dark blue-cyan
+  gotham: {
+    background: "#0c1014",
+    foreground: "#99d1ce",
+    cursor: "#99d1ce",
+    cursorAccent: "#0c1014",
+    selectionBackground: "#99d1ce",
+    selectionForeground: "#0c1014",
+    black: "#0c1014",
+    red: "#c23127",
+    green: "#2aa889",
+    yellow: "#edb443",
+    blue: "#195466",
+    magenta: "#4e5166",
+    cyan: "#33859e",
+    white: "#99d1ce",
+    brightBlack: "#0c1014",
+    brightRed: "#c23127",
+    brightGreen: "#2aa889",
+    brightYellow: "#edb443",
+    brightBlue: "#195466",
+    brightMagenta: "#4e5166",
+    brightCyan: "#33859e",
+    brightWhite: "#99d1ce",
+  },
 };