fix: Unify public-only token filtering in API queries and repo access checks (#37118) (#37773)

backport #37118 

This PR closes remaining `public-only` token gaps in the API by making
the restriction apply consistently across repository, organization,
activity, notification, and authenticated `/api/v1/user/...` routes.

Previously, `public-only` tokens were still able to:
- receive private results from some list/search/self endpoints,
- access repository data through ID-based lookups,
- and reach several authenticated self routes that should remain
unavailable for public-only access.

This change treats `public-only` as a cross-cutting visibility boundary:
- list/search endpoints now filter private resources consistently,
- repository lookups enforce the same restriction even when addressed
indirectly,
- and self routes that inherently expose or mutate private account state
now reject `public-only` tokens.

---
Generated by a coding agent with Codex 5.2

Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Claude (Opus 4.7) <noreply@anthropic.com>
Co-authored-by: Nicolas <bircni@icloud.com>

routers/api/v1/repo/repo.go

@@ -131,9 +131,6 @@ func Search(ctx *context.APIContext) {
 	//     "$ref": "#/responses/validationError"
 
 	private := ctx.IsSigned && (ctx.FormString("private") == "" || ctx.FormBool("private"))
-	if ctx.PublicOnly {
-		private = false
-	}
 
 	opts := repo_model.SearchRepoOptions{
 		ListOptions:        utils.GetListOptions(ctx),
@@ -149,6 +146,7 @@ func Search(ctx *context.APIContext) {
 		StarredByID:        ctx.FormInt64("starredBy"),
 		IncludeDescription: ctx.FormBool("includeDesc"),
 	}
+	opts.ApplyPublicOnly(ctx.PublicOnly)
 
 	if ctx.FormString("template") != "" {
 		opts.Template = optional.Some(ctx.FormBool("template"))
@@ -567,6 +565,10 @@ func GetByID(ctx *context.APIContext) {
 		}
 		return
 	}
+	if !ctx.TokenCanAccessRepo(repo) {
+		ctx.APIErrorNotFound()
+		return
+	}
 
 	permission, err := access_model.GetDoerRepoPermission(ctx, repo, ctx.Doer)
 	if err != nil {
@@ -1254,6 +1256,7 @@ func ListRepoActivityFeeds(ctx *context.APIContext) {
 		Date:           ctx.FormString("date"),
 		ListOptions:    listOptions,
 	}
+	opts.ApplyPublicOnly(ctx.PublicOnly)
 
 	feeds, count, err := feed_service.GetFeeds(ctx, opts)
 	if err != nil {