MCP compatibility for AI agents: server registry, JSON-RPC client, gateway, run-time tool catalog

Agents can now use Model Context Protocol servers. End to end:
- SharedKernel seam IMcpGateway (ListToolsAsync / CallToolAsync) + McpToolDescriptor / McpToolResult,
  so the Assembler discovers and can invoke MCP tools without referencing Integrations' tables.
- Integrations: McpServerConfig (org-scoped, owner-only; auth headers AES-GCM encrypted, never
  returned — only their names) + AddMcpServers migration. McpClient: a dependency-free Streamable-HTTP
  JSON-RPC 2.0 client (initialize → notifications/initialized → tools/list / tools/call), carrying the
  Mcp-Session-Id and parsing both application/json and text/event-stream replies. McpGateway resolves
  an org's servers, decrypts headers server-side, and is best-effort: an unreachable server is logged
  and skipped, never failing the run. CRUD + connectivity-test endpoints (create/test/delete owner-only
  via ManageApiKeys; list via ConfigureAgents to bind).
- OrgBoard: Agent gains McpServerIds (uuid[]; migration backfills existing agents to empty) flowing
  through ConfigureAgent + AgentRunContext.
- Assembler: AgentRunExecutor lists the agent's MCP tools (best-effort) and PromptAssembler renders a
  "# Tools (MCP)" catalog — labelled as data, never instructions — and records it in the run trace.
- Client: SeatsPage gains an MCP servers card (add/test/delete, encrypted auth header) and a per-agent
  MCP server multi-select; api client gains del().

Note: discovery + the governed call gateway are in place now; the autonomous model-driven tool-call
loop (model emits tool_calls → gated execution → feedback) needs a tool-calling model client and is
the next increment — the stub model can't drive it.

Verified: ArchitectureTests 8/8, IntegrationTests 53/53 (McpClientTests: JSON-RPC handshake/session,
json + SSE; McpServerRegistryTests: owner-only, encrypted-header-never-returned, graceful test,
Member 403; PromptAssemblerMcpTests: catalog + trace, omitted when empty), client build green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/Modules/TeamUp.Modules.OrgBoard/Endpoints/OrgBoardEndpoints.cs

@@ -343,7 +343,7 @@ internal static class OrgBoardEndpoints
 
     private static AgentResponse ToAgent(Agent agent) => new(
         agent.Id, agent.SeatId, agent.Name, agent.Monogram, agent.Autonomy.ToString(),
-        agent.ApiConfigId, agent.FallbackApiConfigId, agent.SkillKeys, agent.Docs);
+        agent.ApiConfigId, agent.FallbackApiConfigId, agent.SkillKeys, agent.McpServerIds, agent.Docs);
 
     private static async Task<IResult> CreateSeat(
         CreateSeatRequest request, ICurrentUser user, IPermissionService permissions,
@@ -422,7 +422,7 @@ internal static class OrgBoardEndpoints
         agent ??= new Agent(seat.Id, now);
         agent.Configure(
             request.Name.Trim(), request.Monogram, request.Autonomy, request.ApiConfigId,
-            request.FallbackApiConfigId, request.SkillKeys ?? [], request.Docs ?? [], now);
+            request.FallbackApiConfigId, request.SkillKeys ?? [], request.McpServerIds ?? [], request.Docs ?? [], now);
 
         if (isNew)
         {