feat: add diagnostic log endpoint for revisions and implement download functionality

Introduced a new endpoint `GET /revisions/{revision_id}/diagnostic-log` to retrieve detailed diagnostic logs for specific revisions. Implemented the corresponding handler to generate and return the log in a structured format. Additionally, updated the frontend to include a download button for the diagnostic log, enhancing user accessibility to revision data.

internal/httpapi/server_test.go

@@ -124,6 +124,34 @@ func TestAPIRefreshApplyJobsBundle(t *testing.T) {
 		}
 	})
 
+	t.Run("diagnostic log for revision", func(t *testing.T) {
+		req, _ := http.NewRequest(http.MethodGet, base+"/v1/revisions/"+rev+"/diagnostic-log", nil)
+		req.Header.Set("Authorization", "Bearer opkey")
+		resp, err := client.Do(req)
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer resp.Body.Close()
+		if resp.StatusCode != http.StatusOK {
+			b, _ := io.ReadAll(resp.Body)
+			t.Fatalf("status %d: %s", resp.StatusCode, b)
+		}
+		if got := resp.Header.Get("Content-Type"); !strings.Contains(got, "text/plain") {
+			t.Fatalf("unexpected content-type: %q", got)
+		}
+		raw, _ := io.ReadAll(resp.Body)
+		body := string(raw)
+		for _, needle := range []string{
+			"EvoBGP revision diagnostic log",
+			"revision_id=" + rev,
+			"## Raw rows",
+		} {
+			if !strings.Contains(body, needle) {
+				t.Fatalf("diagnostic log missing %q", needle)
+			}
+		}
+	})
+
 	t.Run("list modules peers speakers", func(t *testing.T) {
 		for _, path := range []string{"/v1/modules", "/v1/peers", "/v1/speakers"} {
 			req, _ := http.NewRequest(http.MethodGet, base+path, nil)