feat(api): add project APIs (#38691)

Adds REST APIs for project boards for repo, org and user scopes, using
as much shared code as possible for all 3 scopes.

Fixes: https://github.com/go-gitea/gitea/issues/14299
Fixes: https://github.com/go-gitea/gitea/issues/31769
Fixes: https://github.com/go-gitea/gitea/issues/35921
Replaces: https://github.com/go-gitea/gitea/pull/37518
Replaces: https://github.com/go-gitea/gitea/pull/36008
Replaces: https://github.com/go-gitea/gitea/pull/28111
Replaces: https://github.com/go-gitea/gitea/pull/31768
Signed-off-by: silverwind <me@silverwind.io>
Co-authored-by: Supen.Huang <supen.huang@qq.com>
Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Ember <ember@mubergacres.com>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: beardev-in <abhinav.edulakanti@gmail.com>

models/project/column_list.go

@@ -0,0 +1,42 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package project
+
+import (
+	"context"
+
+	"gitea.dev/models/db"
+)
+
+// CountColumns returns the total number of columns for a project
+func CountColumns(ctx context.Context, projectID int64) (int64, error) {
+	return db.GetEngine(ctx).Where("project_id=?", projectID).Count(&Column{})
+}
+
+// GetColumns returns a list of columns for a project with pagination
+func GetColumns(ctx context.Context, projectID int64, opts db.ListOptions) (ColumnList, error) {
+	columns := make([]*Column, 0, opts.PageSize)
+	s := db.GetEngine(ctx).Where("project_id=?", projectID).OrderBy("sorting, id")
+	if !opts.IsListAll() {
+		db.SetSessionPagination(s, &opts)
+	}
+	if err := s.Find(&columns); err != nil {
+		return nil, err
+	}
+	return columns, nil
+}
+
+func GetColumnsByIDs(ctx context.Context, projectID int64, columnsIDs []int64) (ColumnList, error) {
+	columns := make([]*Column, 0, 5)
+	if len(columnsIDs) == 0 {
+		return columns, nil
+	}
+	if err := db.GetEngine(ctx).
+		Where("project_id =?", projectID).
+		In("id", columnsIDs).
+		OrderBy("sorting").Find(&columns); err != nil {
+		return nil, err
+	}
+	return columns, nil
+}