feat(gitea): IssueTracker client + inject into brain server (#52)

Implements the IssueTracker port as a real Gitea REST client (#49c) — the
new outbound dependency the brain server gains for capture.

- CreateIssue / CommentIssue / CloseIssue(+optional closing comment) over
  the Gitea API. Owner is the const "mathias", never caller-supplied, so
  a caller cannot redirect a write to another owner's repo.
- Token read once at construction (BRAIN_GITEA_TOKEN), held in the struct,
  travels only in the Authorization header — never logged or in argv.
  Error messages carry status + truncated body, never the token
  (regression-tested). gitea.New returns nil when URL or token is unset,
  so missing config = tracker disabled via one nil check.
- Injected into the MCP server behind the capture.IssueTracker interface
  via WithIssueTracker (constructor injection, swappable/testable); main
  wires it from BRAIN_GITEA_URL (default https://git.d-ma.be) +
  BRAIN_GITEA_TOKEN. Consumed by the capture use-case in #53.

Tests use httptest transports: create (owner+auth header asserted),
comment, close with/without comment, error path that proves the token
never leaks into an error string.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

ingestion/internal/gitea/gitea_test.go

@@ -0,0 +1,117 @@
+package gitea_test
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/mathiasbq/hyperguild/ingestion/internal/gitea"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+const testToken = "super-secret-token-value"
+
+func TestNewNilWhenUnconfigured(t *testing.T) {
+	assert.Nil(t, gitea.New("", testToken))
+	assert.Nil(t, gitea.New("https://git.example", ""))
+}
+
+func TestCreateIssueForcesOwnerAndAuth(t *testing.T) {
+	var gotPath, gotAuth, gotBody string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		gotPath = r.URL.Path
+		gotAuth = r.Header.Get("Authorization")
+		b, _ := io.ReadAll(r.Body)
+		gotBody = string(b)
+		assert.Equal(t, http.MethodPost, r.Method)
+		w.WriteHeader(http.StatusCreated)
+		_ = json.NewEncoder(w).Encode(map[string]any{"number": 42, "html_url": "https://git.d-ma.be/mathias/hyperguild/issues/42"})
+	}))
+	defer srv.Close()
+
+	c := gitea.New(srv.URL, testToken)
+	require.NotNil(t, c)
+	ref, err := c.CreateIssue(context.Background(), "hyperguild", "Do the thing", "details")
+	require.NoError(t, err)
+
+	assert.Equal(t, "/api/v1/repos/mathias/hyperguild/issues", gotPath, "owner forced to mathias")
+	assert.Equal(t, "token "+testToken, gotAuth)
+	assert.Contains(t, gotBody, "Do the thing")
+	assert.Equal(t, "hyperguild", ref.Repo)
+	assert.Equal(t, 42, ref.Number)
+	assert.Contains(t, ref.URL, "/issues/42")
+}
+
+func TestCommentIssue(t *testing.T) {
+	var gotPath string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		gotPath = r.URL.Path
+		w.WriteHeader(http.StatusCreated)
+		_ = json.NewEncoder(w).Encode(map[string]any{"html_url": "https://git/c/1"})
+	}))
+	defer srv.Close()
+
+	ref, err := gitea.New(srv.URL, testToken).CommentIssue(context.Background(), "hyperguild", 7, "a comment")
+	require.NoError(t, err)
+	assert.Equal(t, "/api/v1/repos/mathias/hyperguild/issues/7/comments", gotPath)
+	assert.Equal(t, 7, ref.Number)
+}
+
+func TestCloseIssueWithComment(t *testing.T) {
+	var paths []string
+	var states []string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		paths = append(paths, r.Method+" "+r.URL.Path)
+		if r.Method == http.MethodPatch {
+			var body map[string]any
+			b, _ := io.ReadAll(r.Body)
+			_ = json.Unmarshal(b, &body)
+			states = append(states, body["state"].(string))
+		}
+		w.WriteHeader(http.StatusOK)
+		_ = json.NewEncoder(w).Encode(map[string]any{"number": 9, "html_url": "https://git/i/9"})
+	}))
+	defer srv.Close()
+
+	ref, err := gitea.New(srv.URL, testToken).CloseIssue(context.Background(), "hyperguild", 9, "closing because done")
+	require.NoError(t, err)
+	assert.Equal(t, 9, ref.Number)
+	// Comment posted first, then state PATCHed to closed.
+	assert.Contains(t, paths, "POST /api/v1/repos/mathias/hyperguild/issues/9/comments")
+	assert.Contains(t, paths, "PATCH /api/v1/repos/mathias/hyperguild/issues/9")
+	assert.Equal(t, []string{"closed"}, states)
+}
+
+func TestCloseIssueNoComment(t *testing.T) {
+	var commented bool
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if strings.HasSuffix(r.URL.Path, "/comments") {
+			commented = true
+		}
+		w.WriteHeader(http.StatusOK)
+		_ = json.NewEncoder(w).Encode(map[string]any{"number": 3, "html_url": "https://git/i/3"})
+	}))
+	defer srv.Close()
+
+	_, err := gitea.New(srv.URL, testToken).CloseIssue(context.Background(), "hyperguild", 3, "")
+	require.NoError(t, err)
+	assert.False(t, commented, "empty comment ⇒ no comment POST")
+}
+
+func TestErrorPathDoesNotLeakToken(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.WriteHeader(http.StatusInternalServerError)
+		_, _ = w.Write([]byte("boom"))
+	}))
+	defer srv.Close()
+
+	_, err := gitea.New(srv.URL, testToken).CreateIssue(context.Background(), "hyperguild", "t", "b")
+	require.Error(t, err)
+	assert.NotContains(t, err.Error(), testToken, "token must never appear in an error message")
+	assert.Contains(t, err.Error(), "500")
+}