feat(tools): code_search (single-repo)

Adds SearchCode to gitea.Client and code_search MCP tool for single-repo
code search via GET /api/v1/repos/{owner}/{repo}/search?type=code.
Fan-out placeholder returns ErrValidation (lands in 7.3).

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

internal/tools/code_search_test.go

@@ -0,0 +1,73 @@
+package tools_test
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"gitea.d-ma.be/mathias/gitea-mcp/internal/allowlist"
+	"gitea.d-ma.be/mathias/gitea-mcp/internal/gitea"
+	"gitea.d-ma.be/mathias/gitea-mcp/internal/tools"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestCodeSearchSingleRepo(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		assert.Equal(t, "/api/v1/repos/mathias/infra/search", r.URL.Path)
+		assert.Equal(t, "ListRepos", r.URL.Query().Get("q"))
+		assert.Equal(t, "code", r.URL.Query().Get("type"))
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{
+			"data":[{
+				"path":"internal/gitea/repos.go",
+				"snippet":"func (c *Client) ListRepos",
+				"html_url":"http://gitea.example.com/mathias/infra/src/branch/main/internal/gitea/repos.go",
+				"score":3.0
+			}],
+			"ok":true
+		}`))
+	}))
+	defer srv.Close()
+
+	tool := tools.NewCodeSearch(gitea.NewClient(srv.URL, "tok"), allowlist.New([]string{"mathias"}))
+	out, err := tool.Call(context.Background(), json.RawMessage(`{"q":"ListRepos","owner":"mathias","repo":"infra"}`))
+	require.NoError(t, err)
+
+	var result struct {
+		Results []struct {
+			Repo    string  `json:"repo"`
+			Path    string  `json:"path"`
+			Snippet string  `json:"snippet"`
+			Score   float64 `json:"score"`
+		} `json:"results"`
+	}
+	require.NoError(t, json.Unmarshal(out, &result))
+	require.Len(t, result.Results, 1)
+	assert.Equal(t, "mathias/infra", result.Results[0].Repo)
+	assert.Equal(t, "internal/gitea/repos.go", result.Results[0].Path)
+	assert.Equal(t, "func (c *Client) ListRepos", result.Results[0].Snippet)
+}
+
+func TestCodeSearchAllowlistRejects(t *testing.T) {
+	tool := tools.NewCodeSearch(gitea.NewClient("http://unused", ""), allowlist.New([]string{"mathias"}))
+	_, err := tool.Call(context.Background(), json.RawMessage(`{"q":"foo","owner":"evil","repo":"infra"}`))
+	require.Error(t, err)
+}
+
+func TestCodeSearchRequiresQ(t *testing.T) {
+	tool := tools.NewCodeSearch(gitea.NewClient("http://unused", ""), allowlist.New([]string{"mathias"}))
+	_, err := tool.Call(context.Background(), json.RawMessage(`{"owner":"mathias","repo":"infra"}`))
+	require.Error(t, err)
+	assert.True(t, errors.Is(err, gitea.ErrValidation))
+}
+
+func TestCodeSearchFanOutNotYetImplemented(t *testing.T) {
+	tool := tools.NewCodeSearch(gitea.NewClient("http://unused", ""), allowlist.New([]string{"mathias"}))
+	_, err := tool.Call(context.Background(), json.RawMessage(`{"q":"foo","owner":"mathias"}`))
+	require.Error(t, err)
+	assert.True(t, errors.Is(err, gitea.ErrValidation))
+}