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/ushebrew.flc

@@ -0,0 +1,33 @@
+flc2a
+# implements a natural mapping from the U.S. keyboard
+# to Hebrew characters in the Ivrit font.
+# Note that capital letters remain unchanged.
+
+t a \0x05d0
+t b \0x05d1
+t g \0x05d2
+t d \0x05d3
+t h \0x05d4
+t v \0x05d5
+t z \0x05d6
+t c \0x05d7
+t t \0x05d8
+t y \0x05d9
+t k \0x05db
+t f \0x05da
+t l \0x05dc
+t m \0x05de
+t o \0x05dd
+t n \0x05e0
+t i \0x05df
+t e \0x05e1
+t _ \0x05e2
+t p \0x05e4
+t u \0x05e3
+t j \0x05e6
+t w \0x05e5
+t q \0x05e7
+t r \0x05e8
+t s \0x05e9
+t x \0x05ea
+t ~ \-3