feat: remove ProjectMember, add expose RBAC role, attach/detach-server commands

- Remove ProjectMember model entirely (RBAC manages project access)
- Add 'expose' RBAC role for /mcp-config endpoint access (edit implies expose)
- Rename CLI flags: --llm-provider → --proxy-mode-llm-provider, --llm-model → --proxy-mode-llm-model
- Add attach-server / detach-server CLI commands (mcpctl --project NAME attach-server SERVER)
- Add POST/DELETE /api/v1/projects/:id/servers endpoints for server attach/detach
- Remove members from backup/restore, apply, get, describe
- Prisma migration to drop ProjectMember table

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

src/db/prisma/migrations/20260223120000_remove_project_members/migration.sql

@@ -0,0 +1,8 @@
+-- DropForeignKey
+ALTER TABLE "ProjectMember" DROP CONSTRAINT IF EXISTS "ProjectMember_projectId_fkey";
+
+-- DropForeignKey
+ALTER TABLE "ProjectMember" DROP CONSTRAINT IF EXISTS "ProjectMember_userId_fkey";
+
+-- DropTable
+DROP TABLE IF EXISTS "ProjectMember";

src/db/prisma/schema.prisma

@@ -24,7 +24,6 @@ model User {
   sessions           Session[]
   auditLogs          AuditLog[]
   ownedProjects      Project[]
-  projectMemberships ProjectMember[]
   groupMemberships   GroupMember[]
 
   @@index([email])
@@ -181,7 +180,6 @@ model Project {
 
   owner   User            @relation(fields: [ownerId], references: [id], onDelete: Cascade)
   servers ProjectServer[]
-  members ProjectMember[]
 
   @@index([name])
   @@index([ownerId])
@@ -199,18 +197,6 @@ model ProjectServer {
   @@unique([projectId, serverId])
 }
 
-model ProjectMember {
-  id        String   @id @default(cuid())
-  projectId String
-  userId    String
-  createdAt DateTime @default(now())
-
-  project Project @relation(fields: [projectId], references: [id], onDelete: Cascade)
-  user    User    @relation(fields: [userId], references: [id], onDelete: Cascade)
-
-  @@unique([projectId, userId])
-}
-
 // ── MCP Instances (running containers) ──
 
 model McpInstance {