feat(validation): implement confirmation and support voting with duplicate prevention #8

Summary

Implement the dual-channel community validation and voting system that distinguishes personal confirmation from general community support, backed by database uniqueness constraints.

Context

ProblemSpot emphasizes that personal confirmation ("I experience this too") is distinct from community support ("I support addressing this"). Neither vote type alone constitutes authoritative verification.

Scope

1. Interactive Voting Components (components/voting/):
   • Distinct personal confirmation button and community support button.
   • Optimistic state updates and real-time counter updates.
2. Server Actions / API Handlers:
   • Toggle vote action handling vote cast and retraction.
   • Guard against duplicate voting via database unique constraints.
3. Validation Summary Widget:
   • Visual summary on problem cards and detail pages showing both metrics distinctly.

Acceptance Criteria

• Users can cast and toggle personal confirmation and community support votes independently.
• Database prevents duplicate vote entries.
• Counters update optimistically.