refactor: replace orchestrator/verifier chain with direct LiteLLM calls

Drop the three-layer Claude subprocess orchestration (local model →
Claude verifier → cloud escalation). Skills now call LiteLLM directly
and return plain text to Claude Code, which decides what to do with it.

- Delete executor, orchestrator, verifier, result, attempts packages
- Simplify LiteLLMExecutor: Run(Request)→Result becomes Complete(model,sys,user)→(string,int64,error)
- Replace ExecutorFn with CompleteFunc in all 6 skill configs
- Rewrite all skill handlers to call Complete and return {"text","model","duration_ms"}
- Simplify config/models: remove Verifier/LlamaSwapURL, add ModelFor
- Bump version to v0.5.0

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

internal/skills/spec/handlers_test.go

@@ -6,7 +6,6 @@ import (
 	"encoding/json"
 	"testing"
 
-	iexec "github.com/mathiasbq/supervisor/internal/exec"
 	"github.com/mathiasbq/supervisor/internal/skills/spec"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -33,29 +32,22 @@ func TestSpecRequiresRequirements(t *testing.T) {
 	assert.ErrorContains(t, err, "requirements")
 }
 
-func TestSpecCallsExecutor(t *testing.T) {
-	called := false
+func TestSpecCallsCompleteFunc(t *testing.T) {
 	var capturedTask string
-	fakeFn := func(_ context.Context, req iexec.Request) (iexec.Result, error) {
-		called = true
-		capturedTask = req.TaskPrompt
-		return iexec.Result{
-			Status: "pass", Phase: "spec", Skill: "spec",
-			FilePath: "/tmp/proj/docs/login-spec.md",
-			Verified: true, ModelUsed: "self", Message: "spec written: login feature",
-		}, nil
+	fakeFn := func(_ context.Context, _, _, user string) (string, int64, error) {
+		capturedTask = user
+		return "# OAuth2 Login Spec\n\n## Overview\nImplement OAuth2 login flow.", 110, nil
 	}
 
-	sk := spec.New(spec.Config{SkillPrompt: "spec rules", ExecutorFn: fakeFn, SessionsDir: t.TempDir()})
+	sk := spec.New(spec.Config{SkillPrompt: "spec rules", CompleteFunc: fakeFn, SessionsDir: t.TempDir()})
 	out, err := sk.Handle(context.Background(), "spec", json.RawMessage(
 		`{"project_root":"/tmp/proj","requirements":"add OAuth2 login","output_path":"docs/login-spec.md"}`,
 	))
 	require.NoError(t, err)
-	assert.True(t, called)
 	assert.Contains(t, capturedTask, "OAuth2 login")
 	assert.Contains(t, capturedTask, "docs/login-spec.md")
 
-	var result iexec.Result
+	var result map[string]any
 	require.NoError(t, json.Unmarshal(out, &result))
-	assert.Equal(t, "spec", result.Phase)
+	assert.Contains(t, result["text"], "OAuth2 Login Spec")
 }