Migrate db, auth to mcdsl; remove mcias client dependency

- db.Open: delegate to mcdsl/db.Open
- db.Migrate: convert to mcdsl/db.Migration format, delegate
- auth: type aliases for TokenInfo/Authenticator/Config from mcdsl,
  re-export error sentinels, Logout helper
- cmd/server: construct auth.Authenticator from Config (not mcias.Client)
- server/routes.go logout: use auth.Logout(authenticator, token)
- grpcserver/auth.go: same logout pattern, fix Login return type
  (time.Time not string)
- webserver: replace mcias.Client with mcdsl/auth for service token
  validation; resolveUser degrades to raw UUID (TODO: restore when
  mcias client library is properly tagged)
- Dockerfiles: bump to golang:1.25-alpine, remove gcc/musl-dev,
  add VERSION build arg
- Deploy: add docker-compose-rift.yml with localhost-only port mapping
- Remove git.wntrmute.dev/kyle/mcias/clients/go dependency entirely
- All tests pass, net -185 lines

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

internal/server/routes.go

@@ -9,7 +9,7 @@ import (
 
 	"github.com/go-chi/chi/v5"
 
-	mcias "git.wntrmute.dev/kyle/mcias/clients/go"
+
 
 	"git.wntrmute.dev/kyle/metacrypt/internal/audit"
 	"git.wntrmute.dev/kyle/metacrypt/internal/auth"
@@ -236,13 +236,7 @@ func (s *Server) handleLogin(w http.ResponseWriter, r *http.Request) {
 
 func (s *Server) handleLogout(w http.ResponseWriter, r *http.Request) {
 	token := extractToken(r)
-	client, err := mcias.New(s.cfg.MCIAS.ServerURL, mcias.Options{
-		CACertPath: s.cfg.MCIAS.CACert,
-		Token:      token,
-	})
-	if err == nil {
-		_ = s.auth.Logout(client)
-	}
+	_ = auth.Logout(s.auth, token)
 
 	// Clear cookie.
 	http.SetCookie(w, &http.Cookie{