feat(ui): improve accessibility and empty state on players page

[myarichuk]

🎨 Palette: Improve Players Page Accessibility and Empty State

💡 What:

• Added an aria-label to the search input.
• Added explicit type="button" attributes to the "Analyze Party" and "Add Player" buttons.
• Updated the empty state descriptive text with the .text-tertiary class and .mb-4 spacing.

🎯 Why:

• The search input was missing a descriptive label for screen readers.
• The action buttons lacked a type attribute, which could unintentionally trigger form submissions if placed inside or near a form.
• The empty state text typography and spacing were inconsistent with the repository's design system patterns (which uses .text-tertiary for explanatory empty state text).

📸 Before/After:
Visually, the empty state text is now correctly styled as tertiary text, and keyboard/screen reader users can now properly identify the search input.

♿ Accessibility:

• Screen readers will now announce "Search players or characters" when focusing the search input instead of just reading the placeholder or ignoring it.

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PR created automatically by Jules for task 3012329362149405755 started by @myarichuk

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