feat: filter and browse products by Pokémon

[hjacque]

Goal

Let users filter the product table by Pokémon and browse all cards featuring a given Pokémon — both as a primary subject and as a cameo. Turns the Pokémon entity (#87) and card associations (#88) into a browseable dimension of the product catalog.

Scope

• Filter the main product table by Pokémon (single or multi-select)
• "Show all cards featuring Pikachu" — including cards where Pikachu is a cameo
• Role filter: featured only vs. including cameos

Design notes

• Filter UI alongside the existing franchise / set / type filters
• Pokémon selector should be searchable (100+ Pokémon in the database)
• Multi-select: filter by multiple Pokémon at once (e.g. all cards featuring Charizard or Blastoise)
• URL state via nuqs (consistent with existing filter patterns)

Blocked by

• feat: Pokemon entity — seed all Pokémon in database #87 — Pokémon entity (Pokémon must exist in database)
• feat: link Pokémon to cards (featured + cameos) #88 — Pokémon ↔ card associations (cards must be linked to Pokémon)