chore: dead-code ratchet is failing on main (knip count 81 > baseline 78)

[isadeks]

Summary

scripts/check-deadcode-ratchet.mjs fails on main today, independent of any open PR: the knip issue count is 81 vs the committed baseline of 78 in knip-baseline.json. Because the same ratchet runs inside mise run build (which the repo mandates green before commit), every contributor's local build is currently red on main.

Discovered while fixing the dead-export nit on #503 — the count is +3 over baseline from exports/deps that drifted unused via other merges, not from any single PR. Stack A's #503 removes its own contribution (82→81) but can't get the ratchet back to 78 on its own.

The 3 categories over baseline

• Unused devDependencies (3): @types/pdf-parse (cdk), markdown-link-check (docs), @astrojs/check (root).
• Plus drifted unused exports/types (run yarn knip for the current list; several pre-date this and are already in the count).

Options

1. Remove the genuinely-dead items and lower the baseline in the same PR (the file's own guidance — "when the count drops, lower this value to lock in the gain"), or
2. Re-baseline to the current honest count if the findings are intentional (suppress per-category false positives in knip.json, not the baseline).

Acceptance criteria

• node scripts/check-deadcode-ratchet.mjs exits 0 on main.
• knip-baseline.json reflects the true post-cleanup count.