og:description falls back to the site blurb for a character with no details, species or owner

A character with no details, no species and no owner gets the generic site blurb as its og:description and meta description, rather than anything about the character.

Where

apps/frontend/src/pages/CharacterPage.tsx builds the description as:

description:
  character?.details ||
  [
    character?.species?.name,
    character?.owner ? `owned by ${character.owner.username}` : null,
  ]
    .filter(Boolean)
    .join(" · "),

With all three absent the array is empty, join returns "", and applyPageMeta (src/lib/pageMeta.ts) treats empty as absent:

const description = meta.description ? truncate(meta.description) : DEFAULT_DESCRIPTION;

so the page describes itself as "A home for original characters: profiles, art galleries, species and the communities built around them."

Why it happens

All three inputs are genuinely optional. speciesId and ownerId are both nullable on the Character model — a character kicked from its species, or one whose owner was deleted (onDelete: SetNull), reaches this state, and details is free text nobody has to fill in. The codebase already models ownerless characters as "orphaned" throughout, so this isn't a hypothetical.

Impact

Low. The title is still correct — the character's name — so the card and the tab are not wrong, just uninformative in the second line. Affects the meta description Google indexes and, once server-side rendering exists, the unfurl.

Fix sketch

Give the character page its own last-resort description rather than falling through to the site's, e.g. "A character on CharDB". The reverted backend renderer did exactly that; the client-side path was never given the equivalent.

Worth deciding at the same time whether applyPageMeta's empty-string-means-absent behaviour is right in general, or whether callers should pass null explicitly when they mean "no description".

Follow-up from #365. Third of three copy issues noted at merge; this is the second.

Start in apps/frontend/src/pages/CharacterPage.tsx and trace how its description reaches applyPageMeta in src/lib/pageMeta.ts. Check the empty-details, missing-species, and missing-owner case, then verify that it receives a character-specific fallback while existing details, species, and owner descriptions remain unchanged.