[Fluent] Accessibility / Contrast Issue fixes

[dkoleva-infra]

Continuing our accessibility improvements initiative, we refined color contrasts in several components to ensure better legibility and alignment with WCAG guidelines.

Affected are the following components in Fluent:

• Bottom Navigation
• Calendar
• Date Picker
• Grid
• List
• Stepper

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Bottom Navigation:

[Dark mode]

• icon & text - changed to primary.300

---

Calendar:

[Light mode]

• week numbers text - changed to grays.700
• week days text - changed to grays.700
• inactive days text - changed to grays.700

[Dark mode]

• week numbers background - changed to grays.100

Link to calendar handoff.

---

Date Picker:

[Light mode]

• week numbers text - changed to grays.700
• week days text - changed to grays.700
• inactive days text - changed to grays.700

[Dark mode]

• week numbers background - changed to grays.100

---

Grids:

[Light mode]

Grid Features/Group Area - connector icons color - changed to grays.600
Grid Features/GroupBy Row - badge text - changed to grays.700
Grid Features/Toolbar - toolbar title - changed to grays.700
Grid Item/Cell-Summary - text color - changed to primary.600
Grid Item/Data Grid-Column - cancel icons - changed to grays.600

[Dark mode]

Data Grid Item/Cell-Summary - text color - changed to primary.300

---

List:

[Light mode]

List heading - text color - changed to secondary.700

---

Stepper:

[Dark mode]

Type: Invalid Normal State - text color - changed to error.50
Type: Invalid Hover State - text color - changed to rror.50
Type: Invalid Focus State - text color - changed to error.50
Type: Focus State - background opacity of 50% - changed to background opacity 40%

Link to Fluent UI Kit