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/db/db.go

@@ -3,41 +3,13 @@ package db
 
 import (
 	"database/sql"
-	"fmt"
-	"os"
 
-	_ "modernc.org/sqlite"
+	mcdsldb "git.wntrmute.dev/kyle/mcdsl/db"
 )
 
-// Open opens or creates a SQLite database at the given path with secure
-// file permissions (0600) and WAL mode enabled.
+// Open opens or creates a SQLite database at the given path with the
+// standard Metacircular pragmas (WAL, FK, busy timeout) and 0600
+// permissions.
 func Open(path string) (*sql.DB, error) {
-	// Ensure the file has restrictive permissions if it doesn't exist yet.
-	if _, err := os.Stat(path); os.IsNotExist(err) {
-		f, err := os.OpenFile(path, os.O_CREATE|os.O_WRONLY, 0600) //nolint:gosec
-		if err != nil {
-			return nil, fmt.Errorf("db: create file: %w", err)
-		}
-		_ = f.Close()
-	}
-
-	db, err := sql.Open("sqlite", path)
-	if err != nil {
-		return nil, fmt.Errorf("db: open: %w", err)
-	}
-
-	// Enable WAL mode and foreign keys.
-	pragmas := []string{
-		"PRAGMA journal_mode=WAL",
-		"PRAGMA foreign_keys=ON",
-		"PRAGMA busy_timeout=5000",
-	}
-	for _, p := range pragmas {
-		if _, err := db.Exec(p); err != nil {
-			_ = db.Close()
-			return nil, fmt.Errorf("db: pragma %q: %w", p, err)
-		}
-	}
-
-	return db, nil
+	return mcdsldb.Open(path)
 }