Phase 0: scheduleragent + mcp-server read-only agent framework

Complete the natural-language scheduler agent's Phase 0 read-only pipeline:

Task #2 (API Key auth mechanism):
- New store/apikey.go: APIKey store (hash, validate, expiry)
- controllers/apikey.go: GenerateAPIKey finally persists + registers RBAC role
- controllers/auth.go: GetUsernameFromToken recognizes xce_ak_ prefix
- middleware/validatehandler.go: isValidToken handles API Key
- config/rbac.yaml: mcp_readonly role (view-only permissions)
- 6 new test files covering unit + integration full-chain

Task #3 (schedulerclient Go library):
- types.go: URM types (URMJob/URMQueue/URMNode/JobStatus/Metrics)
- client.go: read-only Client interface (6 methods)
- httpclient.go: resty-based HTTP implementation
- statusmap.go + _test.go: TDD status mapping (33 tests)

Task #4 (mcp-server binary):
- cmd/main.go: entry, reads XCE_API_URL/XCE_API_KEY, registers 6 MCP tools
- internal/app.go: tool handlers wiring schedulerclient to MCP stdio
- Uses github.com/mark3labs/mcp-go@v0.57.0 for stdio transport

All: go vet clean, go build clean, schedulerclient 33/33 tests pass.
mcp-server binary ~11MB arm64, CGO_ENABLED=0.

Architecture:
  Claude Code --stdio--> mcp-server --HTTP--> apiserver REST API --cgo--> C backend

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

src/frontend/apiserver/router/routers.go

@@ -73,6 +73,14 @@ func Router() *gin.Engine {
 		permHandler := &controllers.PermController{}
 		permsApi.GET("", controllers.RequirePermission("rbac:view"), permHandler.GetPermsInfo)
 	}
+	// ################ case: apikeys route (service-account credentials, e.g. for the
+	// scheduler-agent MCP server; generation is admin-only, gated the same way role
+	// management is)
+	apikeysApi := r.Group("/xce/v1/apikeys")
+	{
+		apikeyHandler := &controllers.APIKeyController{}
+		apikeysApi.POST("", controllers.RequirePermission("rbac:control"), apikeyHandler.GenerateAPIKey)
+	}
 	// ################ case: roles route
 	rolesApi := r.Group("/xce/v1/roles")
 	{