refactor: move extension testing package to pkg/

Move the extension testing package from internal/extensions/test to
pkg/extensions/test to make it publicly importable by external extension
authors.

Changes:
- Moved test package files to pkg/extensions/test/
- Updated all imports from internal/ to pkg/ path:
  - README.md
  - examples/extensions/tool-logger_test.go
  - examples/extensions/extension_test_template.go
  - skills/kit-extensions/SKILL.md
  - www/pages/extensions/testing.md
  - pkg/extensions/test/README.md
  - pkg/extensions/test/harness.go

The test package is now available for external import as:
  github.com/mark3labs/kit/pkg/extensions/test

All tests pass with race detector.

README.md

@@ -362,7 +362,7 @@ package main
 
 import (
     "testing"
-    "github.com/mark3labs/kit/internal/extensions/test"
+    "github.com/mark3labs/kit/pkg/extensions/test"
     "github.com/mark3labs/kit/internal/extensions"
 )
 

examples/extensions/extension_test_template.go

@@ -15,7 +15,7 @@ import (
 	"testing"
 
 	"github.com/mark3labs/kit/internal/extensions"
-	"github.com/mark3labs/kit/internal/extensions/test"
+	"github.com/mark3labs/kit/pkg/extensions/test"
 )
 
 // Test that your extension loads without errors

examples/extensions/tool-logger_test.go

@@ -6,7 +6,7 @@ import (
 	"testing"
 
 	"github.com/mark3labs/kit/internal/extensions"
-	"github.com/mark3labs/kit/internal/extensions/test"
+	"github.com/mark3labs/kit/pkg/extensions/test"
 )
 
 // Test that the tool-logger extension loads and registers handlers

pkg/extensions/test/README.md

@@ -1,6 +1,6 @@
 # Testing Kit Extensions
 
-The `github.com/mark3labs/kit/internal/extensions/test` package provides utilities for testing Kit extensions using standard Go testing patterns.
+The `github.com/mark3labs/kit/pkg/extensions/test` package provides utilities for testing Kit extensions using standard Go testing patterns.
 
 ## Overview
 
@@ -18,7 +18,7 @@ The test package is part of the Kit codebase. Import it in your extension tests:
 ```go
 import (
     "testing"
-    "github.com/mark3labs/kit/internal/extensions/test"
+    "github.com/mark3labs/kit/pkg/extensions/test"
     "github.com/mark3labs/kit/internal/extensions"
 )
 ```
@@ -32,7 +32,7 @@ package main
 
 import (
     "testing"
-    "github.com/mark3labs/kit/internal/extensions/test"
+    "github.com/mark3labs/kit/pkg/extensions/test"
     "github.com/mark3labs/kit/internal/extensions"
 )
 
@@ -336,7 +336,7 @@ package main
 
 import (
     "testing"
-    "github.com/mark3labs/kit/internal/extensions/test"
+    "github.com/mark3labs/kit/pkg/extensions/test"
     "github.com/mark3labs/kit/internal/extensions"
 )
 

pkg/extensions/test/harness.go

@@ -10,7 +10,7 @@
 //
 //	import (
 //	    "testing"
-//	    "github.com/mark3labs/kit/internal/extensions/test"
+//	    "github.com/mark3labs/kit/pkg/extensions/test"
 //	)
 //
 //	func TestMyExtension(t *testing.T) {

skills/kit-extensions/SKILL.md

@@ -930,7 +930,7 @@ package main
 
 import (
     "testing"
-    "github.com/mark3labs/kit/internal/extensions/test"
+    "github.com/mark3labs/kit/pkg/extensions/test"
     "github.com/mark3labs/kit/internal/extensions"
 )
 
@@ -1216,6 +1216,6 @@ func applyMode(ctx ext.Context, active bool, tools []string) {
 - [`internal/extensions/runner.go`](https://github.com/mark3labs/kit/blob/main/internal/extensions/runner.go) — Event dispatch and state management
 - [`internal/extensions/loader.go`](https://github.com/mark3labs/kit/blob/main/internal/extensions/loader.go) — Yaegi interpreter setup
 - [`internal/extensions/symbols.go`](https://github.com/mark3labs/kit/blob/main/internal/extensions/symbols.go) — All types exported to extensions
-- [`internal/extensions/test/`](https://github.com/mark3labs/kit/tree/main/internal/extensions/test) — Testing package with harness, mocks, and assertions
+- [`pkg/extensions/test/`](https://github.com/mark3labs/kit/tree/main/pkg/extensions/test) — Testing package with harness, mocks, and assertions
 - [`examples/extensions/tool-logger_test.go`](https://github.com/mark3labs/kit/blob/main/examples/extensions/tool-logger_test.go) — Complete test example
 - [`examples/extensions/`](https://github.com/mark3labs/kit/tree/main/examples/extensions) — 25+ working example extensions

www/pages/extensions/testing.md

@@ -5,7 +5,7 @@ description: Write unit tests for your Kit extensions using the test package.
 
 # Testing Extensions
 
-Kit provides a testing package (`github.com/mark3labs/kit/internal/extensions/test`) that enables you to write unit tests for your extensions. Tests run outside the Yaegi interpreter but load your extension code into an isolated interpreter instance, allowing you to verify behavior without running the full Kit TUI.
+Kit provides a testing package (`github.com/mark3labs/kit/pkg/extensions/test`) that enables you to write unit tests for your extensions. Tests run outside the Yaegi interpreter but load your extension code into an isolated interpreter instance, allowing you to verify behavior without running the full Kit TUI.
 
 ## Overview
 
@@ -25,7 +25,7 @@ The test package is part of the Kit codebase. Import it in your extension tests:
 ```go
 import (
     "testing"
-    "github.com/mark3labs/kit/internal/extensions/test"
+    "github.com/mark3labs/kit/pkg/extensions/test"
     "github.com/mark3labs/kit/internal/extensions"
 )
 ```
@@ -41,7 +41,7 @@ package main
 
 import (
     "testing"
-    "github.com/mark3labs/kit/internal/extensions/test"
+    "github.com/mark3labs/kit/pkg/extensions/test"
     "github.com/mark3labs/kit/internal/extensions"
 )