feat(settings): Jira config UI — admin config tab + per-user token in Profile

- backend: add parent_ticket field to JiraConfigOut/JiraConfigUpdate/_JIRA_KEYS
- backend: add get_jira_parent_ticket() helper in jira_service; use it in auto_create_test_issue() to set issue parent
- frontend/api: add jira_token_set to UserMeOut, jira_api_token to UserPreferencesUpdate, and full JiraConfigOut/Update types with getJiraConfig/updateJiraConfig/testJiraConnection functions
- frontend: expand ProfileSection with Jira API token password field (show/hide), token status badge, and account-id field
- frontend: add JiraConfigSection component (admin): enabled toggle, URL, project key, parent ticket, save + test connection
- frontend: add Jira tab (admin-only) with Link2 icon in SettingsPage sidebar

backend/app/routers/system.py

@@ -210,6 +210,7 @@ class JiraConfigOut(BaseModel):
     enabled: bool
     url: str
     project_key: str
+    parent_ticket: str
     # Credentials are never returned
 
 
@@ -217,12 +218,14 @@ class JiraConfigUpdate(BaseModel):
     enabled: Optional[bool] = None
     url: Optional[str] = None
     project_key: Optional[str] = None
+    parent_ticket: Optional[str] = None
 
 
 _JIRA_KEYS = {
     "enabled": "jira.enabled",
     "url": "jira.url",
     "project_key": "jira.project_key",
+    "parent_ticket": "jira.parent_ticket",
 }
 
 
@@ -235,12 +238,13 @@ def get_jira_config(
 
     **Requires** the ``admin`` role. Credentials are never returned.
     """
-    from app.services.jira_service import get_jira_url, get_jira_project_key, is_jira_enabled
+    from app.services.jira_service import get_jira_url, get_jira_project_key, is_jira_enabled, get_jira_parent_ticket
 
     return JiraConfigOut(
         enabled=is_jira_enabled(db),
         url=get_jira_url(db) or "",
         project_key=get_jira_project_key(db) or "",
+        parent_ticket=get_jira_parent_ticket(db) or "",
     )
 
 
@@ -255,7 +259,7 @@ def update_jira_config(
     **Requires** the ``admin`` role. Only provided fields are updated.
     """
     from app.services.jira_service import (
-        upsert_jira_config, get_jira_url, get_jira_project_key, is_jira_enabled,
+        upsert_jira_config, get_jira_url, get_jira_project_key, is_jira_enabled, get_jira_parent_ticket,
     )
 
     update_data = payload.model_dump(exclude_unset=True)
@@ -269,6 +273,7 @@ def update_jira_config(
         enabled=is_jira_enabled(db),
         url=get_jira_url(db) or "",
         project_key=get_jira_project_key(db) or "",
+        parent_ticket=get_jira_parent_ticket(db) or "",
     )