Show total TrackedTime on issue/pull/milestone lists (#26672)

TODOs:
- [x] write test for `GetIssueTotalTrackedTime`
- [x] frontport kitharas template changes and make them mobile-friendly

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![image](6713da97-201f-4217-8588-4c4cec157171)

![image](3a45aba8-26b5-4e6a-b97d-68bfc2bf9024)

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*Sponsored by Kithara Software GmbH*

models/issues/tracked_time.go

@@ -15,6 +15,7 @@ import (
 	"code.gitea.io/gitea/modules/util"
 
 	"xorm.io/builder"
+	"xorm.io/xorm"
 )
 
 // TrackedTime represents a time that was spent for a specific issue.
@@ -325,3 +326,46 @@ func GetTrackedTimeByID(ctx context.Context, id int64) (*TrackedTime, error) {
 	}
 	return time, nil
 }
+
+// GetIssueTotalTrackedTime returns the total tracked time for issues by given conditions.
+func GetIssueTotalTrackedTime(ctx context.Context, opts *IssuesOptions, isClosed bool) (int64, error) {
+	if len(opts.IssueIDs) <= MaxQueryParameters {
+		return getIssueTotalTrackedTimeChunk(ctx, opts, isClosed, opts.IssueIDs)
+	}
+
+	// If too long a list of IDs is provided,
+	// we get the statistics in smaller chunks and get accumulates
+	var accum int64
+	for i := 0; i < len(opts.IssueIDs); {
+		chunk := i + MaxQueryParameters
+		if chunk > len(opts.IssueIDs) {
+			chunk = len(opts.IssueIDs)
+		}
+		time, err := getIssueTotalTrackedTimeChunk(ctx, opts, isClosed, opts.IssueIDs[i:chunk])
+		if err != nil {
+			return 0, err
+		}
+		accum += time
+		i = chunk
+	}
+	return accum, nil
+}
+
+func getIssueTotalTrackedTimeChunk(ctx context.Context, opts *IssuesOptions, isClosed bool, issueIDs []int64) (int64, error) {
+	sumSession := func(opts *IssuesOptions, issueIDs []int64) *xorm.Session {
+		sess := db.GetEngine(ctx).
+			Table("tracked_time").
+			Where("tracked_time.deleted = ?", false).
+			Join("INNER", "issue", "tracked_time.issue_id = issue.id")
+
+		return applyIssuesOptions(sess, opts, issueIDs)
+	}
+
+	type trackedTime struct {
+		Time int64
+	}
+
+	return sumSession(opts, issueIDs).
+		And("issue.is_closed = ?", isClosed).
+		SumInt(new(trackedTime), "tracked_time.time")
+}