feat(cli,config): add preview flag for live commit subject display

use --preview in cli or preview = true in toml

Author: ttw225

commitizen/cli.py

@@ -164,6 +164,11 @@ def __call__(
                         "type": int,
                         "help": "Set the length limit of the commit message; 0 for no limit.",
                     },
+                    {
+                        "name": ["--preview"],
+                        "action": "store_true",
+                        "help": "Show live first-line (subject) preview while typing.",
+                    },
                     {
                         "name": ["--"],
                         "action": "store_true",

commitizen/defaults.py

@@ -65,6 +65,7 @@ class Settings(TypedDict, total=False):
     version_type: str | None
     version: str | None
     breaking_change_exclamation_in_title: bool
+    preview: bool
 
 
 CONFIG_FILES: tuple[str, ...] = (
@@ -115,6 +116,7 @@ class Settings(TypedDict, total=False):
     "extras": {},
     "breaking_change_exclamation_in_title": False,
     "message_length_limit": 0,  # 0 for no limit
+    "preview": False,
 }
 
 MAJOR = "MAJOR"