feat: Email Team button + custom-email dialog on project page

Adds a PROJECT_TEAM recipient type to the message router (resolver
returns team members + project lead) and an "Email Team" button on
the admin project detail page that opens a self-contained dialog
matching the look of /admin/messages: subject, body (pre-filled
with "Hello [Project Title] team,\n\n"), live HTML preview iframe,
"Send test to me" + "Send to N" actions.

The composer reuses the existing message.previewEmail and
message.send tRPC procedures end-to-end — no parallel email
infrastructure introduced.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/unit/message-recipient-project-team.test.ts

@@ -0,0 +1,60 @@
+import { afterAll, beforeAll, describe, expect, it } from 'vitest'
+import { prisma, createCaller } from '../setup'
+import {
+  createTestUser, createTestProgram, createTestProject, cleanupTestData, uid,
+} from '../helpers'
+import { messageRouter } from '../../src/server/routers/message'
+
+describe('message.previewRecipients — PROJECT_TEAM', () => {
+  let programId: string
+  let admin: { id: string; email: string; role: 'SUPER_ADMIN' }
+  let projectId: string
+  const userIds: string[] = []
+
+  beforeAll(async () => {
+    const program = await createTestProgram({ name: `proj-team-${uid()}` })
+    programId = program.id
+
+    const lead = await createTestUser('APPLICANT')
+    userIds.push(lead.id)
+    const project = await createTestProject(programId, { title: 'TestProj' })
+    projectId = project.id
+    await prisma.project.update({ where: { id: projectId }, data: { submittedByUserId: lead.id } })
+
+    const member1 = await createTestUser('APPLICANT')
+    const member2 = await createTestUser('APPLICANT')
+    userIds.push(member1.id, member2.id)
+    await prisma.teamMember.createMany({
+      data: [
+        { id: uid('tm'), projectId, userId: member1.id, role: 'MEMBER' },
+        { id: uid('tm'), projectId, userId: member2.id, role: 'MEMBER' },
+      ],
+    })
+
+    const a = await createTestUser('SUPER_ADMIN')
+    userIds.push(a.id)
+    admin = { id: a.id, email: a.email, role: 'SUPER_ADMIN' }
+  })
+
+  afterAll(async () => {
+    await cleanupTestData(programId, userIds)
+  })
+
+  it('counts the lead + 2 team members', async () => {
+    const caller = createCaller(messageRouter, admin)
+    const result = await caller.previewRecipients({
+      recipientType: 'PROJECT_TEAM',
+      recipientFilter: { projectId },
+    })
+    expect(result.totalApplicants).toBe(3)
+  })
+
+  it('returns 0 when projectId is missing', async () => {
+    const caller = createCaller(messageRouter, admin)
+    const result = await caller.previewRecipients({
+      recipientType: 'PROJECT_TEAM',
+      recipientFilter: {},
+    })
+    expect(result.totalApplicants).toBe(0)
+  })
+})