perf(ci): per-package compiled cache, test shards, single generator pass

[apresmoi]

What moved

packages/objects/src/prepared-data/
  archived-camera.ts          <- archived-camera@1 format, parser, constants (from spice/bake)
  object-text.ts              <- object-text@1 format, parser, constants (from site/bake)
  prepared-destinations.ts    <- prepared-destinations@1 format, parser, constants (from site/bake)

Writers and readers in bake, spice, telescope-cli and site import these from @cssearth/objects; no re-export shims remain.

Ledger and baseline

• Schema-format ledger: 56 entries before, 55 after (prepared-destinations removed).
• archived-camera and object-text shrink to bake-only Python entries with a stated reason, pinned by conformance tests.
• Architecture baseline: unchanged (baseline.json not modified; no new cycles).

Checks

• Clean build (all dist/ wiped, pnpm install --frozen-lockfile, pnpm build:packages) and node .github/scripts/ci/build-ci.mts lint
• pnpm check:architecture and node --test .github/scripts/architecture/*.test.mts
• pnpm check:body-references with packages/objects/dist moved away
• pnpm typecheck:pr (includes astro check), pnpm typecheck:tests, pnpm typecheck:nebula
• Universe nebula job selection (node labs/nebula/run.mts test ...)
• Objects, spice, bake (juno), site and telescope-cli tests
• Byte-identical serialized outputs against the previous owners
• git diff --check origin/main

See PR rules.