fix: polish buttons to match figma design

[jvsena42]

Description

This PR polishes the Primary, Secondary, and Tertiary buttons to match the Figma design specs:

1. Aligns padding, gap, border, text color, and shape per button size variant
2. Adds a glass blur effect to SecondaryButton using a custom glassBlur modifier
3. Fixes the PrimaryButton top shine highlight to follow the pill shape contour instead of rendering as a clipped flat rect
4. Makes PrimaryButton shadow elevation size-dependent (16dp large, 4dp small)
5. Replaces TertiaryButton's Material ripple with clean alpha-dim press feedback
6. Implements a custom GradientCircularProgressIndicator for loading states

Preview

Screen_recording_20260403_132257.webm

QA Notes

1. Primary Button

   • Verify pill shape (64dp corners), 32dp horizontal padding on large, 16dp on small
   • Confirm top shine follows the rounded contour (no flat cut-off at corners)
   • Small variant should have a subtle shadow (4dp), large a stronger one (16dp)
   • Disabled state should match enabled dimensions

2. Secondary Button

   • Large: 2dp Gray4 border, 28dp padding, 6dp icon-text gap
   • Small: 1dp White16 border, 16dp padding, 8dp gap, White64 text
   • Subtle glass blur effect visible on both sizes
   • Background tint at 1% white opacity

3. Tertiary Button

   • No ripple effect on tap — only alpha dim feedback
   • Text color White80 (enabled), White32 (disabled)
   • No border, no background

4. Loading states — all three buttons show gradient progress indicator when loading

5. Disabled states — verify icons dim to White32, borders become transparent

[jvsena42]

I tried using Haze library for the SecondaryButton but didn't get a good result

[claude]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.