Add tm_server with SQLite, Svelte UI, and task-master TUI sync.

Introduces the web backend (auth, RBAC, project tokens, revisions),
YouTrack-or-taskmaster backend choice in the TUI, and a first-pass
embedded Svelte UI. The frontend is functional but needs a major rework.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/sqlite/crypto.go

@@ -0,0 +1,58 @@
+package sqlite
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"crypto/sha256"
+	"fmt"
+	"io"
+)
+
+func normalizeSecret(secret []byte) []byte {
+	if len(secret) == 0 {
+		// Deterministic fallback for local/dev; production should set TASK_MASTER_SECRET.
+		sum := sha256.Sum256([]byte("task-master-dev-secret"))
+		return sum[:]
+	}
+	sum := sha256.Sum256(secret)
+	return sum[:]
+}
+
+// EncryptToken seals plaintext with AES-GCM.
+func (db *DB) EncryptToken(plain string) ([]byte, error) {
+	block, err := aes.NewCipher(db.Secret)
+	if err != nil {
+		return nil, err
+	}
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+	nonce := make([]byte, gcm.NonceSize())
+	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
+		return nil, err
+	}
+	return gcm.Seal(nonce, nonce, []byte(plain), nil), nil
+}
+
+// DecryptToken opens an AES-GCM blob.
+func (db *DB) DecryptToken(blob []byte) (string, error) {
+	block, err := aes.NewCipher(db.Secret)
+	if err != nil {
+		return "", err
+	}
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return "", err
+	}
+	if len(blob) < gcm.NonceSize() {
+		return "", fmt.Errorf("token ciphertext too short")
+	}
+	nonce, ct := blob[:gcm.NonceSize()], blob[gcm.NonceSize():]
+	plain, err := gcm.Open(nil, nonce, ct, nil)
+	if err != nil {
+		return "", err
+	}
+	return string(plain), nil
+}