Denunciar button

[GonzaloGM]

Summary

Adds a Denunciar action across the app so users can open a new support ticket pre-filled as a report (category=report, type Denuncia). No backend changes: the existing support ticket API and report type are reused.

Frontend (carpoolear)

New behaviour

• Trip detail (driver panel): Denunciar next to Ver perfil, same row and height, centered labels; hidden when viewing your own trip.
• User profile: Denunciar on other users’ profiles (hidden on your own).
• Conversation chat (desktop header): Denunciar beside the participant name in 1:1 chats; hidden for group chats.
  All buttons use a flag icon and route to Nuevo ticket (ticket-new) with:
• category=report
• Prefilled subject (e.g. Denuncia usuario #5 - Juan, Denuncia viaje #99 - conductor …)

Implementation

• reportTicketRoute.js — helpers to build route + subject lines
• TicketNew.vue — reads category and subject from query on load
• Shared .btn-report styles (flex layout, icon spacing, profile icon float fix)
• i18n: denunciar (ES/EN)
• View/unit tests for route helper, TicketNew, TripDriver, ProfileInfo, ConversationChat

Closes #119