chore(ci): refresh v2 models.dev snapshot on a schedule - #50030

Same workflow as #50010, opened against dev because schedule: triggers only fire from the repository's default branch.

Every 30 minutes (or on manual dispatch) this checks out v2, runs packages/core/script/update-models-snapshot.ts, and if packages/core/src/models-dev/snapshot.txt changed, commits it straight to v2 as the OpenCode bot — the same setup-git-committer + pull --rebase + push HEAD:v2 pattern nix-hashes.yml uses. Nothing on dev is read or written except this workflow file itself.

Context: that snapshot is v2's boot-time catalog floor on a cold cache. It went unrefreshed from 2026-08-11 until #50009, so every v2 release in between shipped a catalog ~1,500 models behind live.

Notes:

• Uses oven-sh/setup-bun directly instead of the repo's setup-bun composite: the script is dependency-free (fetch + Bun.write), so the monorepo bun install would be wasted every half hour.
• The script refuses to write when the response has fewer than 100 providers, so a models.dev error page never gets committed.
• Each bot commit is a push to v2, which triggers v2's publish.yml (dev channel), same as nix-hashes commits do today. models.dev changes a few times a day, so expect a few extra dev publishes. Appending [skip ci] to the commit message is a one-line change if that's unwanted.
• chore(ci): refresh bundled models.dev snapshot on a schedule #50010 carries the identical file on v2. Merging both is harmless — only the default branch's copy schedules, so there's no double run — and it means the cron keeps working unchanged when v2 becomes the default.