feat: modernize progress indicators

[adrcotfas]

• Modernize progress indicators according to the MD3 Specs and reuse existing MD theme foundation tokens (motion, shape etc) where appropriate.
• Extract component tokens to a separate file for easier maintenance

Current State

Existing "Activity Indicator" and "Progress Bar" components correspond to MD3 Progress Indicators.

Activity Indicator

MD3 spec: Progress indicators (Circular)
Specs link: https://m3.material.io/components/progress-indicators/specs

Color tokens

• No track color. MD3 requires a track arc behind the indicator (token: secondaryContainer); only primary is rendered

Spacing / sizing

• Stroke width is size / 10 (2.4dp @ small, 4.8dp @ large). MD3 specifies a fixed 4dp stroke for both indicator and track

Behavior

• Arc ends are square (border clipping technique). MD3 requires rounded stroke caps
• No track rendered. MD3 always shows the inactive track arc
• M3 Expressive wavy circular and linear indicators not implemented

Notes

• Rename to match MD3: CircularProgressIndicator and move to a “Progress Indicators” directory together with Linear Progress Indicator.
• Entire rendering approach is MD2-era (two clipped half-border views). MD3-compliant implementation needs SVG or canvas-based arc for rounded caps and track

Progress Bar

MD3 spec: Linear progress indicator
Specs link: https://m3.material.io/components/progress-indicators/specs

Color tokens

• Active indicator: color || theme.colors.primary ✅
• Track: theme.colors.surfaceVariant; spec requires secondaryContainer ❌
• No stop indicator rendered; spec defines a stop indicator at 100% (color primary)

Spacing / sizing

• Height: 4dp ✅
• Track has no borderRadius; spec corner.full requires borderRadius: 2 for 4dp height
• Active indicator fill has no borderRadius; same issue as track
• No 4dp horizontal inset from screen edges; spec shows 4dp padding on each side
• Configurable thickness not supported (M3 Expressive)
• Wavy shape (amplitude 3dp, wavelength 40dp, height 10dp) not supported (M3 Expressive)

Behavior

• Determinate mode: progress value animates via scaleX ✅
• Indeterminate mode: looping translate + scaleX animation ✅
• Visibility fade in/out ✅
• RTL support ✅
• Stop indicator not shown at the end of the track

Notes

• Should be renamed LinearProgressIndicator and placed in a shared ProgressIndicator/ directory alongside ActivityIndicator (circular), matching MD3 naming
• ProgressBar name and the color prop (which bypasses the token system) are library-level issues to address at rename time