chore: remove stale my-lang drift directory

developer-ecosystem/my-lang/ was a standalone git repo (not a registered
submodule) carrying a 192-line Typing.v with 3 `Admitted.` — the canonical
copy at developer-ecosystem/nextgen-languages/my-lang/proofs/verification/
coq/Typing.v is 745 lines with 0 `Admitted.` (all proofs closed with Qed.).

The stale copy was dual-truth drift: same project at two paths, neither
registered as a submodule of developer-ecosystem, neither synced against
the other. Removed per 2026-04-19 dangerous-pattern inventory cleanup.

Canonical my-lang is unchanged at its two registered locations:
- /var/mnt/eclipse/repos/my-lang/ (root-level submodule)
- /var/mnt/eclipse/repos/developer-ecosystem/nextgen-languages/my-lang/
  (nested inside the nextgen-languages monorepo)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: hyperpolymath