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>

templates/shared/issuelist.tmpl

@@ -76,10 +76,10 @@
 							<span class="gt-ellipsis">{{.Milestone.Name}}</span>
 						</a>
 					{{end}}
-					{{if .Project}}
-						<a class="project flex-text-inline tw-max-w-[300px]" href="{{.Project.Link ctx}}">
-							{{svg .Project.IconName 14}}
-							<span class="gt-ellipsis">{{.Project.Title}}</span>
+					{{range $project := .Projects}}
+						<a class="project flex-text-inline tw-max-w-[300px]" href="{{$project.Link ctx}}">
+							{{svg $project.IconName 14}}
+							<span class="gt-ellipsis">{{$project.Title}}</span>
 						</a>
 					{{end}}
 					{{if .Ref}}{{/* TODO: RemoveIssueRef: see "repo/issue/branch_selector_field.tmpl" */}}