Allow multiple projects per issue and pull requests (#36784)

Add ability to add and remove multiple projects per issue
and pull request.

Resolve #12974

---------

Signed-off-by: Icy Avocado <avocado@ovacoda.com>
Co-authored-by: Tyrone Yeh <siryeh@gmail.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: OpenCode (gpt-5.2-codex) <opencode@openai.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Claude (Opus 4.7) <noreply@anthropic.com>

modules/indexer/issues/db/options.go

@@ -13,6 +13,7 @@ import (
 	"code.gitea.io/gitea/modules/container"
 	"code.gitea.io/gitea/modules/indexer/issues/internal"
 	"code.gitea.io/gitea/modules/optional"
+	"code.gitea.io/gitea/modules/util"
 )
 
 func ToDBOptions(ctx context.Context, options *internal.SearchOptions) (*issue_model.IssuesOptions, error) {
@@ -65,8 +66,7 @@ func ToDBOptions(ctx context.Context, options *internal.SearchOptions) (*issue_m
 		ReviewRequestedID:  convertID(options.ReviewRequestedID),
 		ReviewedID:         convertID(options.ReviewedID),
 		SubscriberID:       convertID(options.SubscriberID),
-		ProjectID:          convertID(options.ProjectID),
-		ProjectColumnID:    convertID(options.ProjectColumnID),
+		ProjectIDs:         util.Iif(options.NoProjectOnly, []int64{db.NoConditionID}, options.ProjectIDs),
 		IsClosed:           options.IsClosed,
 		IsPull:             options.IsPull,
 		IncludedLabelNames: nil,