Fix broken $refs from the bambulab schema underscore-rename, remove stale v2/

- print.schema.json, _ams.schema.json, _ams_unit.schema.json still
  pointed at the pre-rename filenames (ams.schema.json, ams_unit.schema.json,
  ams_tray.schema.json) after the underscore-prefix split - fixed all
  three, verified with a full jsonschema + referencing validation run
  against real captures (get_version, pushall, a full print/ams/xcam
  report with both empty and loaded trays) plus negative tests.
- _upgrade_state.schema.json: fixed its $id (pointed at report/info/,
  file lives under report/print/) and its title (said "ModuleInfo",
  clearly copy-pasted from _module_info.schema.json). Wired it into
  print.schema.json as the print report's `upgrade_state` property -
  the file existed but nothing referenced it yet.
- Deleted schemas/bambulab/v2/, which had been recreated as stale,
  broken copies of an older v1 (missing the envelope allOf, missing
  the underscore renames, $ids still pointing at v1/ paths) - the
  repo's own README documents v2 as intentionally removed until V2's
  wire format is known to differ from V1's.
- Updated schemas/bambulab/README.md's layout tree and inheritance-
  example reference, both stale after the underscore rename.
- Removed stray tsc -b build output (packages/ts-types/src/*.d.ts/js)
  that isn't meant to be committed (outDir is dist/, gitignored).

Verified: cargo check clean (continuum-proxy, continuum-ai-worker,
rust-types), tsc clean (continuum-backend, continuum-common ts-core),
10/10 JSON Schema validation cases passing.

.env.example

@@ -1,4 +1,4 @@
-# continuum-schemas has no runtime — it only emits generated types/structs.
+# continuum-schemas has no runtime - it only emits generated types/structs.
 # This file is kept for consistency with the other Continuum repos.
 
 # Optional: private registry token, only needed if packages/* are ever