fix: wire nilaway as a golangci-lint module plugin

nilaway is not bundled in golangci-lint v2.x due to false-positive
risk (see uber-go/nilaway#4045). Use the module plugin system instead:

- Add .custom-gcl.yml with the plugin definition (go.uber.org/nilaway)
- Configure nilaway as a custom linter in .golangci.yaml with
  include-pkgs scoped to this module

Author: eeran-cs

.custom-gcl.yml

@@ -0,0 +1,6 @@
+# golangci-lint >= v1.57.0 is required for module plugin support.
+version: v1.57.0
+plugins:
+  - module: "go.uber.org/nilaway"
+    import: "go.uber.org/nilaway/cmd/gclplugin"
+    version: latest

.golangci.yaml

@@ -22,6 +22,13 @@ linters:
     - unconvert
     - unparam
     - unused
+  settings:
+    custom:
+      nilaway:
+        type: module
+        description: Static analysis tool to detect potential nil panics in Go code.
+        settings:
+          include-pkgs: "github.com/crowdstrike/falcon-cli"
   exclusions:
     generated: lax
     presets: