refactor(core): move `compact_size()` from `common.py` to `tools.py`

diff --git a/python/src/trezorlib/testing/common.py b/python/src/trezorlib/testing/common.py
index 5c883e32..f3601f8b 100644
--- a/python/src/trezorlib/testing/common.py
+++ b/python/src/trezorlib/testing/common.py
@@ -13,31 +13,6 @@ BRGeneratorType = Generator[None, messages.ButtonRequest, None]
 PRIVATE_KEYS_DEV = [byte * 32 for byte in (b"\xdd", b"\xde", b"\xdf")]
 
 
-def compact_size(n: int) -> bytes:
-    """
-    Encode an integer using Bitcoin's compact size format.
-
-    Args:
-        n (int): The integer to encode.
-
-    Returns:
-        bytes: The encoded integer.
-
-    Raises:
-        ValueError: If n is not in the range 0..2^64-1.
-    """
-    if n < 0 or n > 0xFFFF_FFFF_FFFF_FFFF:
-        raise ValueError("compact_size supports integers in range 0..2^64-1")
-    if n < 253:
-        return n.to_bytes(1, "little")
-    elif n < 0x1_0000:
-        return bytes([253]) + n.to_bytes(2, "little")
-    elif n < 0x1_0000_0000:
-        return bytes([254]) + n.to_bytes(4, "little")
-    else:
-        return bytes([255]) + n.to_bytes(8, "little")
-
-
 def get_text_possible_pagination(debug: "DebugLink", br: messages.ButtonRequest) -> str:
     """
     Read all text content from the device, handling possible pagination.
diff --git a/python/src/trezorlib/tools.py b/python/src/trezorlib/tools.py
index b882c5af..66e4c5d2 100644
--- a/python/src/trezorlib/tools.py
+++ b/python/src/trezorlib/tools.py
@@ -44,6 +44,31 @@ HARDENED_FLAG = 1 << 31
 Address = t.NewType("Address", list[int])
 
 
+def compact_size(n: int) -> bytes:
+    """
+    Encode an integer using Bitcoin's compact size format.
+
+    Args:
+        n (int): The integer to encode.
+
+    Returns:
+        bytes: The encoded integer.
+
+    Raises:
+        ValueError: If n is not in the range 0..2^64-1.
+    """
+    if n < 0 or n > 0xFFFF_FFFF_FFFF_FFFF:
+        raise ValueError("compact_size supports integers in range 0..2^64-1")
+    if n < 253:
+        return n.to_bytes(1, "little")
+    elif n < 0x1_0000:
+        return bytes([253]) + n.to_bytes(2, "little")
+    elif n < 0x1_0000_0000:
+        return bytes([254]) + n.to_bytes(4, "little")
+    else:
+        return bytes([255]) + n.to_bytes(8, "little")
+
+
 def H_(x: int) -> int:
     """
     Shortcut function that "hardens" a number in a BIP44 path.
diff --git a/tests/device_tests/evolu/common.py b/tests/device_tests/evolu/common.py
index 141c854d..01ad4c64 100644
--- a/tests/device_tests/evolu/common.py
+++ b/tests/device_tests/evolu/common.py
@@ -8,8 +8,8 @@ from trezorlib import evolu
 from trezorlib.debuglink import DebugSession as Session
 from trezorlib.debuglink import TrezorTestContext as Client
 from trezorlib.messages import EvoluDelegatedIdentityKey, ThpCredentialResponse
-from trezorlib.testing.common import compact_size
 from trezorlib.thp import curve25519
+from trezorlib.tools import compact_size
 
 TEST_randomness = os.urandom(32)
 TEST_host_static_private_key = curve25519.get_private_key(TEST_randomness)
diff --git a/tests/device_tests/evolu/test_sign_registration.py b/tests/device_tests/evolu/test_sign_registration.py
index 1ca78134..f8ee51cd 100644
--- a/tests/device_tests/evolu/test_sign_registration.py
+++ b/tests/device_tests/evolu/test_sign_registration.py
@@ -4,7 +4,7 @@ from ecdsa import NIST256p, SigningKey, VerifyingKey
 from trezorlib import evolu
 from trezorlib.debuglink import TrezorTestContext as Client
 from trezorlib.exceptions import TrezorFailure
-from trezorlib.testing.common import compact_size
+from trezorlib.tools import compact_size
 
 from ..certificate import check_signature_optiga
 from .common import get_delegated_identity_key, get_invalid_proof, get_proof
diff --git a/tests/device_tests/payment_req.py b/tests/device_tests/payment_req.py
index 6b33735a..8a3215fb 100644
--- a/tests/device_tests/payment_req.py
+++ b/tests/device_tests/payment_req.py
@@ -5,7 +5,7 @@ from ecdsa import NIST256p, SigningKey
 
 from trezorlib import messages
 from trezorlib.client import Session
-from trezorlib.testing.common import compact_size
+from trezorlib.tools import compact_size
 
 SLIP44_ID_UNDEFINED = 0xFFFF_FFFF
 
diff --git a/tests/device_tests/test_authenticate_device.py b/tests/device_tests/test_authenticate_device.py
index a9c58b91..6815f284 100644
--- a/tests/device_tests/test_authenticate_device.py
+++ b/tests/device_tests/test_authenticate_device.py
@@ -3,7 +3,7 @@ from cryptography import x509
 
 from trezorlib import device, exceptions, messages
 from trezorlib.debuglink import DebugSession as Session
-from trezorlib.testing.common import compact_size
+from trezorlib.tools import compact_size
 
 from .certificate import (
     check_signature_mcu,