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/1Row.flf

@@ -0,0 +1,218 @@
+flf2a$ 2 1 8 -1 13
+
+                  1row font by unknown
+                 =======================
+
+
+-> Conversion to FigLet font by MEPH. (Part of ASCII Editor Service Pack I)
+   (http://studenten.freepage.de/meph/ascii/ascii/editor/_index.htm)
+-> Defined: ASCII code alphanumeric
+-> Uppercase characters only.
+
+
+Was a part of a '1row' font collection. Author unknown.
+
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