feat(ui): Build reusable ProgressBar and CircularProgress components

[rindicomfort]

Summary

Closes #267

Implements two shared progress indicator components requested in issue #267, following all project conventions (TypeScript strict, Tailwind-only, barrel exports, ARIA attributes).

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Changes

ProgressBar — frontend/src/components/ui/ProgressBar/

• Linear progress bar with smooth transition-all duration-500 width animation
• Props: value (0–100), label?, color? (blue | green | yellow | red), size? (sm | md | lg)
• Full ARIA support: role="progressbar", aria-valuenow, aria-valuemin, aria-valuemax
• Color variants map to existing Tailwind design tokens (accent-blue, accent-green, etc.)

CircularProgress — frontend/src/components/ui/CircularProgress/

• SVG-based circular progress arc using stroke-dashoffset technique
• Smooth transition-all duration-500 animation on the arc
• Center label renders the current percentage inside the SVG
• Props: value (0–100), size? (px, default 80), strokeWidth? (default 6), label?
• Full ARIA support: role="progressbar", aria-valuenow, aria-valuemin, aria-valuemax

Root barrel frontend/src/components/index.ts

• Exports both components and their types under the // UI section

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Acceptance Criteria

• ProgressBar animates to correct fill width
• CircularProgress arc matches the value via stroke-dashoffset
• Both have correct ARIA attributes (role, aria-valuenow, aria-valuemin, aria-valuemax)
• All prop variations typed and exported
• No TypeScript errors (strict: true compliant)
• Tailwind-only styling, no per-component CSS
• Barrel index.ts in each component folder
• Exported from root components/index.ts