perf: Various performance regression fixes (#38078)

Fixes five N+1 / O(n) query patterns found across common user paths.
Each uses a bulk query that already existed elsewhere in the codebase.

| Location | Problem | Introduced in |
| -------------------------------- |
-------------------------------------------------------------------------------------------------------------------------------
| ------------- |
| `IssueList.LoadIsRead` | `.In("issue_id")` missing its arg — xorm
generates `WHERE 0=1`, so `IsRead` is **never** set; every issue always
appears unread | #29515 |
| `ParseCommitsWithStatus` | `GetLatestCommitStatus` called once per
commit (O(n) queries on commit list / PR commits tab) | #33605 |
| `getReleaseInfos` (release list) | `GetLatestCommitStatus` called once
per release for CI badges | #29149 |
| User milestone dashboard | O(n×m) nested loop matching milestones to
repos | #26300 |
| `findCodeComments` (PR diff) | `LoadResolveDoer` + `LoadReactions`
called per inline comment — up to ~150 queries on a PR with 50 comments
| #20821 |

---------

Co-authored-by: Lauris B <lauris@nix.lv>

models/issues/comment_list.go

@@ -11,6 +11,7 @@ import (
 	user_model "gitea.dev/models/user"
 	"gitea.dev/modules/container"
 	"gitea.dev/modules/log"
+	"gitea.dev/modules/setting"
 )
 
 // CommentList defines a list of comments
@@ -444,6 +445,73 @@ func (comments CommentList) loadReviews(ctx context.Context) error {
 	return nil
 }
 
+// loadResolveDoers bulk-loads the resolve doer for all code comments that have one.
+func (comments CommentList) loadResolveDoers(ctx context.Context) error {
+	resolveDoerIDs := container.FilterSlice(comments, func(c *Comment) (int64, bool) {
+		return c.ResolveDoerID, c.ResolveDoerID != 0 && c.Type == CommentTypeCode
+	})
+	if len(resolveDoerIDs) == 0 {
+		return nil
+	}
+
+	userMaps, err := user_model.GetUsersMapByIDs(ctx, resolveDoerIDs)
+	if err != nil {
+		return err
+	}
+
+	for _, comment := range comments {
+		if comment.ResolveDoerID == 0 || comment.Type != CommentTypeCode {
+			continue
+		}
+		if u, ok := userMaps[comment.ResolveDoerID]; ok {
+			comment.ResolveDoer = u
+		} else {
+			comment.ResolveDoer = user_model.NewGhostUser()
+		}
+	}
+	return nil
+}
+
+// loadReactions bulk-loads reactions for all comments in the list.
+func (comments CommentList) loadReactions(ctx context.Context, repo *repo_model.Repository) error {
+	if len(comments) == 0 {
+		return nil
+	}
+
+	commentIDs := container.FilterSlice(comments, func(c *Comment) (int64, bool) {
+		return c.ID, c.Reactions == nil
+	})
+	if len(commentIDs) == 0 {
+		return nil
+	}
+
+	var allReactions ReactionList
+	if err := db.GetEngine(ctx).
+		Where("`comment_id` > 0").
+		In("comment_id", commentIDs).
+		In("`type`", setting.UI.Reactions).
+		Asc("issue_id", "comment_id", "created_unix", "id").
+		Find(&allReactions); err != nil {
+		return err
+	}
+
+	if _, err := allReactions.LoadUsers(ctx, repo); err != nil {
+		return err
+	}
+
+	reactByComment := make(map[int64]ReactionList, len(commentIDs))
+	for _, r := range allReactions {
+		reactByComment[r.CommentID] = append(reactByComment[r.CommentID], r)
+	}
+
+	for _, comment := range comments {
+		if comment.Reactions == nil {
+			comment.Reactions = reactByComment[comment.ID]
+		}
+	}
+	return nil
+}
+
 // LoadAttributes loads attributes of the comments, except for attachments and
 // comments
 func (comments CommentList) LoadAttributes(ctx context.Context) (err error) {