feat: add page titles to each route

[Icsylab]

What

Added a useEffect in each of the 4 page components (Home, Login, PostRide, PostIntent) that sets document.title on mount so the browser tab shows which page the user is on. PostRide and PostIntent also needed useEffect added to their React import.

Fixes #4

Type of change

• Bug fix
• New feature
• Breaking change
• Documentation update

Proof of work

• Home page sets document.title = "Splitt"
• Login page sets document.title = "Sign in · Splitt"
• PostRide page sets document.title = "Post a ride · Splitt"
• PostIntent page sets document.title = "Post an intent · Splitt"
• Each title is set inside a useEffect with an empty dependency array

Checklist

• I claimed this issue before starting work
• Branch name follows the convention (feature/, fix/, docs/)
• Commits follow Conventional Commits format
• CI is passing (lint, prettier, build)
• I have self-reviewed my own code
• Any non-obvious decisions are explained with a comment in the code

[PixelKnightDev]

LGTM

[Icsylab]

Thank you for merging!