Migrate module path from kyle/ to mc/ org

All import paths updated from git.wntrmute.dev/kyle/mcias to
git.wntrmute.dev/mc/mcias to match the Gitea organization.
Includes main module and clients/go submodule.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

clients/README.md

@@ -29,7 +29,7 @@ set_pg_creds(account_id, host, port, database, username, password) → void
 | `MciasConflictError` | 409 | Conflict (e.g. duplicate username) |
 | `MciasServerError` | 5xx | Unexpected server error |
 `testdata/` contains canonical JSON response fixtures shared across language tests.
-- `go/` — Go module `git.wntrmute.dev/kyle/mcias/clients/go`
+- `go/` — Go module `git.wntrmute.dev/mc/mcias/clients/go`
 - `rust/` — Rust crate `mcias-client`
 - `lisp/` — ASDF system `mcias-client`
 - `python/` — Python package `mcias_client`