fix: bump team cache when membership changes

The cached team payload embeds a per-user is_member flag, but TeamMember
create/destroy never bumped the team cache key, so warm IDB caches kept
showing a stale membership flag after a user was added to or removed from
a team. Bump the team cache key from the TeamMember lifecycle.

app/models/team_member.rb

@@ -18,6 +18,12 @@ class TeamMember < ApplicationRecord
   belongs_to :user
   belongs_to :team
   validates :user_id, uniqueness: { scope: :team_id }
+
+  # is_member is embedded into the cached team payload (per current user) via
+  # api/v1/models/_team.json.jbuilder, so membership changes must bump the team
+  # cache key. team is safe-navigated because destroying a team cascades here
+  # via destroy_async, by which point the team row is already gone.
+  after_commit -> { team&.account&.update_cache_key('team') }, on: [:create, :destroy]
 end
 
 TeamMember.include_mod_with('Audit::TeamMember')

spec/models/team_member_spec.rb

@@ -5,4 +5,20 @@ RSpec.describe TeamMember do
     it { is_expected.to belong_to(:team) }
     it { is_expected.to belong_to(:user) }
   end
+
+  describe 'team cache invalidation' do
+    let(:team) { create(:team) }
+    let(:user) { create(:user) }
+
+    it 'bumps the team cache key after create' do
+      expect(team.account).to receive(:update_cache_key).with('team')
+      create(:team_member, team: team, user: user)
+    end
+
+    it 'bumps the team cache key after destroy' do
+      team_member = create(:team_member, team: team, user: user)
+      expect(team.account).to receive(:update_cache_key).with('team')
+      team_member.destroy
+    end
+  end
 end