Design polish: fix ticket stub column overlap

[melvincarvalho]

Design POLISH — edits app.css only (no JS, no app files).

Fixes for the .card.ticket-stub layout:

1. Widened stub column 150px → 180px so rotated ticket number has room and doesn't overlap the price badge
2. ADMIT ONE enlarged from .6rem → .78rem, bolder weight (700), wider letter-spacing (.18em) — clearly legible
3. Watermark pushed further into corner with more padding, opacity reduced to .06, added pointer-events: none to prevent stray interaction
4. Perforation margin increased (1.2rem → 1.6rem) so notch circles don't touch adjacent content

Gate: 324 apps pass. Task: #IssDesign2_TicketPolish.