feat: team-based visibility, roles management, unified users, UI fixes

- Add Roles table with CRUD routes and Settings page management
- Unify user management: remove Users page, enhance Team page with
  permission level + role dropdowns
- Add team-based visibility scoping to projects, campaigns, posts,
  tasks, issues, artefacts, and dashboard
- Add team_id to projects and campaigns (create + edit forms)
- Add getUserTeamIds/getUserVisibilityContext helpers
- Fix Budgets modal horizontal scroll (separate linked-to row)
- Add collapsible filter bar to PostProduction page

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/src/i18n/en.json

@@ -662,5 +662,17 @@
   "issues.selectTeam": "Select a team",
   "issues.publicSubmitTeam": "Which team should handle your issue?",
   "team.copyIssueLink": "Copy Issue Link",
-  "team.copyGenericIssueLink": "Copy Public Issue Link"
+  "team.copyGenericIssueLink": "Copy Public Issue Link",
+  "team.permissionLevel": "Permission Level",
+  "team.role": "Role",
+  "team.selectRole": "Select role...",
+  "common.team": "Team",
+  "common.noTeam": "No team",
+  "common.error": "An error occurred",
+  "settings.roles": "Roles",
+  "settings.rolesDesc": "Define job roles like Designer, Strategist, etc. These are assigned to team members separately from permission levels.",
+  "settings.addRole": "Add Role",
+  "settings.roleName": "Role name",
+  "settings.deleteRoleConfirm": "Are you sure you want to delete this role?",
+  "settings.noRoles": "No roles defined yet. Add your first role."
 }