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/indexer_test.go

@@ -416,28 +416,42 @@ func searchIssueInProject(t *testing.T) {
 	}{
 		{
 			SearchOptions{
-				ProjectID: optional.Some(int64(1)),
+				ProjectIDs: []int64{1},
 			},
 			[]int64{5, 3, 2, 1},
 		},
-		{
-			SearchOptions{
-				ProjectColumnID: optional.Some(int64(1)),
-			},
-			[]int64{1},
-		},
-		{
-			SearchOptions{
-				ProjectColumnID: optional.Some(int64(0)), // issue with in default column
-			},
-			[]int64{2},
-		},
 	}
 	for _, test := range tests {
 		issueIDs, _, err := SearchIssues(t.Context(), &test.opts)
 		require.NoError(t, err)
 		assert.Equal(t, test.expectedIDs, issueIDs)
 	}
+
+	// Test filtering for issues with no project assigned using dynamic validation
+	t.Run("no project assigned", func(t *testing.T) {
+		issueIDs, total, err := SearchIssues(t.Context(), &SearchOptions{
+			ProjectIDs: []int64{db.NoConditionID},
+		})
+		require.NoError(t, err)
+		assert.NotEmpty(t, issueIDs)
+		assert.Equal(t, total, int64(len(issueIDs)))
+
+		// Verify each returned issue actually has no project
+		for _, issueID := range issueIDs {
+			issue, err := issues.GetIssueByID(t.Context(), issueID)
+			require.NoError(t, err)
+			err = issue.LoadProjects(t.Context())
+			require.NoError(t, err)
+			assert.Empty(t, issue.Projects, "Issue %d should have no projects", issueID)
+		}
+
+		// Count total issues with no project to verify we got them all
+		allIssues, err := issues.Issues(t.Context(), &issues.IssuesOptions{
+			ProjectIDs: []int64{db.NoConditionID},
+		})
+		require.NoError(t, err)
+		assert.Len(t, issueIDs, len(allIssues), "Should return all issues with no project")
+	})
 }
 
 func searchIssueWithPaginator(t *testing.T) {