feat: protect write endpoints with JWT auth (story #08)

Add bcrypt user file auth, JWT middleware on all write routes, Pinia
authStore with localStorage persistence, login view with redirect
support, and v-if guards on all CRUD controls and admin nav link.

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

backend/internal/middleware/jwt_auth_test.go

@@ -0,0 +1,82 @@
+package middleware_test
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/labstack/echo/v4"
+
+	"osdb/internal/auth"
+	mw "osdb/internal/middleware"
+)
+
+const testSecret = "testsecret"
+
+func okHandler(c echo.Context) error {
+	return c.String(http.StatusOK, "ok")
+}
+
+func TestJWTAuth_NoToken_Returns401(t *testing.T) {
+	e := echo.New()
+	req := httptest.NewRequest(http.MethodPost, "/", nil)
+	rec := httptest.NewRecorder()
+	c := e.NewContext(req, rec)
+
+	h := mw.JWTAuth(testSecret)(okHandler)
+	_ = h(c)
+
+	if rec.Code != http.StatusUnauthorized {
+		t.Errorf("expected 401, got %d", rec.Code)
+	}
+}
+
+func TestJWTAuth_ValidToken_Passes(t *testing.T) {
+	token, _ := auth.GenerateJWT("admin", testSecret)
+
+	e := echo.New()
+	req := httptest.NewRequest(http.MethodPost, "/", nil)
+	req.Header.Set("Authorization", "Bearer "+token)
+	rec := httptest.NewRecorder()
+	c := e.NewContext(req, rec)
+
+	h := mw.JWTAuth(testSecret)(okHandler)
+	if err := h(c); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if rec.Code != http.StatusOK {
+		t.Errorf("expected 200, got %d", rec.Code)
+	}
+}
+
+func TestJWTAuth_InvalidToken_Returns401(t *testing.T) {
+	e := echo.New()
+	req := httptest.NewRequest(http.MethodPost, "/", nil)
+	req.Header.Set("Authorization", "Bearer invalid.token.here")
+	rec := httptest.NewRecorder()
+	c := e.NewContext(req, rec)
+
+	h := mw.JWTAuth(testSecret)(okHandler)
+	_ = h(c)
+
+	if rec.Code != http.StatusUnauthorized {
+		t.Errorf("expected 401, got %d", rec.Code)
+	}
+}
+
+func TestJWTAuth_WrongSecret_Returns401(t *testing.T) {
+	token, _ := auth.GenerateJWT("admin", "other-secret")
+
+	e := echo.New()
+	req := httptest.NewRequest(http.MethodPost, "/", nil)
+	req.Header.Set("Authorization", "Bearer "+token)
+	rec := httptest.NewRecorder()
+	c := e.NewContext(req, rec)
+
+	h := mw.JWTAuth(testSecret)(okHandler)
+	_ = h(c)
+
+	if rec.Code != http.StatusUnauthorized {
+		t.Errorf("expected 401, got %d", rec.Code)
+	}
+}