feat: implement Figlet, Pastel, and Unit tools with a unified layout

- Add Figlet text converter with font selection and history
- Add Pastel color palette generator and manipulation suite
- Add comprehensive Units converter with category-based logic
- Introduce AppShell with Sidebar and Header for navigation
- Modernize theme system with CSS variables and new animations
- Update project configuration and dependencies

public/fonts/figlet-fonts/3x5.flf

@@ -0,0 +1,617 @@
+flf2a$ 6 4 6 -1 4
+3x5 font by Richard Kirk (rak@crosfield.co.uk).
+Ported to figlet, and slightly changed (without permission :-})
+by Daniel Cabeza Gras (bardo@dia.fi.upm.es)
+
+    @
+    @
+    @
+    @
+    @
+    @@
+    @
+ #  @
+ #  @
+ #  @
+    @
+ #  @@
+    @
+# # @
+# # @
+    @
+    @
+    @@
+    @
+# # @
+### @
+# # @
+### @
+# # @@
+    @
+ ## @
+##  @
+### @
+ ## @
+##  @@
+    @
+# # @
+  # @
+ #  @
+#   @
+# # @@
+    @
+ #  @
+#   @
+ ## @
+# # @
+### @@
+    @
+  # @
+ #  @
+#   @
+    @
+    @@
+    @
+  # @
+ #  @
+ #  @
+ #  @
+  # @@
+    @
+#   @
+ #  @
+ #  @
+ #  @
+#   @@
+    @
+ #  @
+### @
+ #  @
+### @
+ #  @@
+    @
+    @
+ #  @
+### @
+ #  @
+    @@
+    @
+    @
+    @
+    @
+ #  @
+#   @@
+    @
+    @
+    @
+### @
+    @
+    @@
+    @
+    @
+    @
+    @
+    @
+ #  @@
+    @
+  # @
+  # @
+ #  @
+#   @
+#   @@
+    @
+### @
+# # @
+# # @
+# # @
+### @@
+    @
+ #  @
+##  @
+ #  @
+ #  @
+### @@
+    @
+### @
+  # @
+### @
+#   @
+### @@
+    @
+### @
+  # @
+ ## @
+  # @
+### @@
+    @
+# # @
+# # @
+### @
+  # @
+  # @@
+    @
+### @
+#   @
+### @
+  # @
+### @@
+    @
+### @
+#   @
+### @
+# # @
+### @@
+    @
+### @
+  # @
+  # @
+  # @
+  # @@
+    @
+### @
+# # @
+### @
+# # @
+### @@
+    @
+### @
+# # @
+### @
+  # @
+### @@
+    @
+    @
+ #  @
+    @
+ #  @
+    @@
+    @
+    @
+ #  @
+    @
+ #  @
+#   @@
+    @
+  # @
+ #  @
+#   @
+ #  @
+  # @@
+    @
+    @
+### @
+    @
+### @
+    @@
+    @
+#   @
+ #  @
+  # @
+ #  @
+#   @@
+    @
+### @
+  # @
+ ## @
+    @
+ #  @@
+    @
+### @
+# # @
+#   @
+### @
+    @@
+    @
+ #  @
+# # @
+### @
+# # @
+# # @@
+    @
+##  @
+# # @
+##  @
+# # @
+##  @@
+    @
+ ## @
+#   @
+#   @
+#   @
+ ## @@
+    @
+##  @
+# # @
+# # @
+# # @
+##  @@
+    @
+### @
+#   @
+##  @
+#   @
+### @@
+    @
+### @
+#   @
+##  @
+#   @
+#   @@
+    @
+ ## @
+#   @
+# # @
+# # @
+ ## @@
+    @
+# # @
+# # @
+### @
+# # @
+# # @@
+    @
+### @
+ #  @
+ #  @
+ #  @
+### @@
+    @
+ ## @
+  # @
+  # @
+# # @
+ #  @@
+    @
+# # @
+# # @
+##  @
+# # @
+# # @@
+    @
+#   @
+#   @
+#   @
+#   @
+### @@
+    @
+# # @
+### @
+### @
+# # @
+# # @@
+    @
+### @
+# # @
+# # @
+# # @
+# # @@
+    @
+ #  @
+# # @
+# # @
+# # @
+ #  @@
+    @
+##  @
+# # @
+##  @
+#   @
+#   @@
+    @
+ #  @
+# # @
+# # @
+ ## @
+  # @@
+    @
+##  @
+# # @
+##  @
+# # @
+# # @@
+    @
+ ## @
+#   @
+ #  @
+  # @
+##  @@
+    @
+### @
+ #  @
+ #  @
+ #  @
+ #  @@
+    @
+# # @
+# # @
+# # @
+# # @
+### @@
+    @
+# # @
+# # @
+# # @
+# # @
+ #  @@
+    @
+# # @
+# # @
+### @
+### @
+# # @@
+    @
+# # @
+# # @
+ #  @
+# # @
+# # @@
+    @
+# # @
+# # @
+ #  @
+ #  @
+ #  @@
+    @
+### @
+  # @
+ #  @
+#   @
+### @@
+    @
+ ## @
+ #  @
+ #  @
+ #  @
+ ## @@
+    @
+#   @
+#   @
+ #  @
+  # @
+  # @@
+    @
+##  @
+ #  @
+ #  @
+ #  @
+##  @@
+    @
+ #  @
+# # @
+    @
+    @
+    @@
+    @
+    @
+    @
+    @
+    @
+### @@
+    @
+#   @
+ #  @
+  # @
+    @
+    @@
+    @
+    @
+ ## @
+# # @
+### @
+    @@
+    @
+#   @
+### @
+# # @
+### @
+    @@
+    @
+    @
+### @
+#   @
+### @
+    @@
+    @
+  # @
+### @
+# # @
+### @
+    @@
+    @
+    @
+### @
+##  @
+### @
+    @@
+    @
+ ## @
+ #  @
+### @
+ #  @
+##  @@
+    @
+    @
+### @
+# # @
+ ## @
+### @@
+    @
+#   @
+### @
+# # @
+# # @
+    @@
+    @
+ #  @
+    @
+ #  @
+ ## @
+    @@
+    @
+ #  @
+    @
+ #  @
+ #  @
+#   @@
+    @
+#   @
+# # @
+##  @
+# # @
+    @@
+    @
+ #  @
+ #  @
+ #  @
+ ## @
+    @@
+    @
+    @
+### @
+### @
+# # @
+    @@
+    @
+    @
+##  @
+# # @
+# # @
+    @@
+    @
+    @
+### @
+# # @
+### @
+    @@
+    @
+    @
+### @
+# # @
+### @
+#   @@
+    @
+    @
+### @
+# # @
+### @
+  # @@
+    @
+    @
+### @
+#   @
+#   @
+    @@
+    @
+    @
+ ## @
+ #  @
+##  @
+    @@
+    @
+ #  @
+### @
+ #  @
+ ## @
+    @@
+    @
+    @
+# # @
+# # @
+### @
+    @@
+    @
+    @
+# # @
+# # @
+ #  @
+    @@
+    @
+    @
+# # @
+### @
+### @
+    @@
+    @
+    @
+# # @
+ #  @
+# # @
+    @@
+    @
+    @
+# # @
+### @
+  # @
+### @@
+    @
+    @
+##  @
+ #  @
+ ## @
+    @@
+    @
+ ## @
+ #  @
+##  @
+ #  @
+ ## @@
+    @
+ #  @
+ #  @
+ #  @
+ #  @
+ #  @@
+    @
+##  @
+ #  @
+ ## @
+ #  @
+##  @@
+    @
+  # @
+### @
+#   @
+    @
+    @@
+    @
+# # @
+ #  @
+# # @
+### @
+# # @@
+    @
+# # @
+### @
+# # @
+# # @
+### @@
+    @
+# # @
+    @
+# # @
+# # @
+### @@
+    @
+# # @
+ ## @
+# # @
+### @
+    @@
+    @
+# # @
+### @
+# # @
+### @
+    @@
+    @
+# # @
+    @
+# # @
+### @
+    @@
+    @
+### @
+##  @
+# # @
+##  @
+#   @@