feat(health): santé du flux — goulots et cartes zombies (issue #9)

app/flow.py: séjours par colonne reconstruits du journal,
médianes, colonne la plus lente; zombies = aucune activité
(journal/Gitea) depuis KANBANTE_ZOMBIE_DAYS (30). Pages /health
et /health/{o}/{r} + actions rapides (commenter/backlog/fermer).

app/config.py

@@ -78,6 +78,9 @@ Environment variables:
                                  column, min_age_days, label, wip_over.
                                  Actions: add_label, notify, move_top.
                                  A rule can never close an issue.
+    KANBANTE_ZOMBIE_DAYS         Days without any activity after
+                                 which an open card is a "zombie"
+                                 on /health (issue #9). Default 30.
 """
 
 import os
@@ -86,7 +89,7 @@ from pathlib import Path
 
 BASE_DIR = Path(__file__).resolve().parent.parent
 
-APP_VERSION = "0.13.0"
+APP_VERSION = "0.14.0"
 
 
 def _env_bool(name: str, default: bool) -> bool:
@@ -154,6 +157,7 @@ class Settings:
     obsigate_mcp_args: str = '{"title": "{title}", "content": "{content}"}'
     briefing_include_standup: bool = False
     rules_raw: str = ""
+    zombie_days: int = 30
 
     @property
     def auth_enabled(self) -> bool:
@@ -198,4 +202,5 @@ def get_settings() -> Settings:
         ),
         briefing_include_standup=_env_bool("KANBANTE_BRIEFING_INCLUDE_STANDUP", False),
         rules_raw=os.getenv("KANBANTE_RULES", ""),
+        zombie_days=_env_int("KANBANTE_ZOMBIE_DAYS", 30),
     )