feat(org): add team visibility so org members can discover teams (#37680)

Closes #37670.

Today, org members in Gitea only see teams they're a member of. In
larger orgs that hurts onboarding and discoverability — there's no way
to look up which team owns what without asking around. GitHub solves
this with a per-team visibility setting; this PR brings the same model
to Gitea.

## What changes

- Every team gets a `visibility` setting:
- `private` *(default)* — only team members and org owners can see the
team. Same as today's behavior.
- `limited` — listable by any member of the organization. Members and
the repos the team has access to are visible too. Non-org-members still
see nothing.
  - `public` — listable by any signed-in user.
- The Owners team visibility is fixed and cannot be changed via
settings.
- Existing teams default to `private`, so this is a no-op for anyone who
doesn't change anything.

## API

- `Team`, `CreateTeamOption`, `EditTeamOption` all gain a `visibility`
field (string enum: `private` | `limited` | `public`).
- `GET /orgs/{org}/teams` and `/orgs/{org}/teams/search` now apply the
same visibility rules as the web UI:
  - site admins and org owners still see every team
- other org members see their own teams plus any `limited` or `public`
team
  - `private` teams are no longer leaked through these endpoints
- Swagger/OpenAPI specs regenerated.

## UI

View from admin2 (not an owner):
<img width="1669" height="726"
src="https://github.com/user-attachments/assets/daf4bccb-644b-4426-b178-71963aeaf73b"
/>

View from admin (owner):

<img width="2559" height="863"
src="https://github.com/user-attachments/assets/4f22cebc-e9df-4fd2-8ed4-724d31fadb7a"
/>

---------

Signed-off-by: bircni <bircni@icloud.com>
Co-authored-by: TheFox0x7 <thefox0x7@gmail.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

routers/api/v1/api.go

@@ -505,41 +505,79 @@ func reqOrgOwnership() func(ctx *context.APIContext) {
 	}
 }
 
-// reqTeamMembership user should be an team member, or a site admin
-func reqTeamMembership() func(ctx *context.APIContext) {
+func teamAccessPrivileged(ctx *context.APIContext) (orgID int64, privileged, ok bool) {
+	if ctx.IsUserSiteAdmin() {
+		return 0, true, true
+	}
+	if ctx.Org.Team == nil {
+		setting.PanicInDevOrTesting("teamAccess: unprepared context")
+		ctx.APIErrorInternal(errors.New("teamAccess: unprepared context"))
+		return 0, false, false
+	}
+
+	orgID = ctx.Org.Team.OrgID
+	isOwner, err := organization.IsOrganizationOwner(ctx, orgID, ctx.Doer.ID)
+	if err != nil {
+		ctx.APIErrorInternal(err)
+		return 0, false, false
+	} else if isOwner {
+		return orgID, true, true
+	}
+
+	isTeamMember, err := organization.IsTeamMember(ctx, orgID, ctx.Org.Team.ID, ctx.Doer.ID)
+	if err != nil {
+		ctx.APIErrorInternal(err)
+		return 0, false, false
+	}
+	return orgID, isTeamMember, true
+}
+
+func denyNonTeamMember(ctx *context.APIContext, orgID int64) {
+	isOrgMember, err := organization.IsOrganizationMember(ctx, orgID, ctx.Doer.ID)
+	if err != nil {
+		ctx.APIErrorInternal(err)
+	} else if isOrgMember {
+		ctx.APIError(http.StatusForbidden, "Must be a team member")
+	} else {
+		ctx.APIErrorNotFound()
+	}
+}
+
+// reqTeamReadAccess allows callers who can list the team to read its metadata.
+// Non-members are admitted by the team's visibility tier and parent org visibility.
+// Not sufficient for mutations — use reqOrgOwnership() or reqTeamMembership() for those.
+func reqTeamReadAccess() func(ctx *context.APIContext) {
 	return func(ctx *context.APIContext) {
-		if ctx.IsUserSiteAdmin() {
+		orgID, privileged, ok := teamAccessPrivileged(ctx)
+		if !ok || privileged {
 			return
 		}
-		if ctx.Org.Team == nil {
-			setting.PanicInDevOrTesting("reqTeamMembership: unprepared context")
-			ctx.APIErrorInternal(errors.New("reqTeamMembership: unprepared context"))
+		if ctx.Org.Organization == nil {
+			setting.PanicInDevOrTesting("reqTeamReadAccess: organization not loaded")
+			ctx.APIErrorInternal(errors.New("reqTeamReadAccess: organization not loaded"))
 			return
 		}
 
-		orgID := ctx.Org.Team.OrgID
-		isOwner, err := organization.IsOrganizationOwner(ctx, orgID, ctx.Doer.ID)
+		visible, err := ctx.Org.Team.CanNonMemberReadMeta(ctx, ctx.Org.Organization.AsUser(), ctx.Doer)
 		if err != nil {
 			ctx.APIErrorInternal(err)
 			return
-		} else if isOwner {
-			return
 		}
+		if !visible {
+			// Not admitted by visibility: 403 for org members, 404 otherwise.
+			denyNonTeamMember(ctx, orgID)
+		}
+	}
+}
 
-		if isTeamMember, err := organization.IsTeamMember(ctx, orgID, ctx.Org.Team.ID, ctx.Doer.ID); err != nil {
-			ctx.APIErrorInternal(err)
-			return
-		} else if !isTeamMember {
-			isOrgMember, err := organization.IsOrganizationMember(ctx, orgID, ctx.Doer.ID)
-			if err != nil {
-				ctx.APIErrorInternal(err)
-			} else if isOrgMember {
-				ctx.APIError(http.StatusForbidden, "Must be a team member")
-			} else {
-				ctx.APIErrorNotFound()
-			}
+// reqTeamMembership user should be a team member, or a site admin
+func reqTeamMembership() func(ctx *context.APIContext) {
+	return func(ctx *context.APIContext) {
+		orgID, privileged, ok := teamAccessPrivileged(ctx)
+		if !ok || privileged {
 			return
 		}
+		denyNonTeamMember(ctx, orgID)
 	}
 }
 
@@ -649,6 +687,17 @@ func orgAssignment(args ...bool) func(ctx *context.APIContext) {
 				}
 				return
 			}
+			if ctx.Org.Organization == nil {
+				ctx.Org.Organization, err = organization.GetOrgByID(ctx, ctx.Org.Team.OrgID)
+				if err != nil {
+					if organization.IsErrOrgNotExist(err) {
+						ctx.APIErrorNotFound()
+					} else {
+						ctx.APIErrorInternal(err)
+					}
+					return
+				}
+			}
 		}
 	}
 }
@@ -1703,25 +1752,31 @@ func Routes() *web.Router {
 			}, reqToken(), reqOrgOwnership())
 		}, tokenRequiresScopes(auth_model.AccessTokenScopeCategoryOrganization), orgAssignment(true), checkTokenPublicOnly())
 		m.Group("/teams/{teamid}", func() {
-			m.Combo("").Get(reqToken(), org.GetTeam).
-				Patch(reqToken(), reqOrgOwnership(), bind(api.EditTeamOption{}), org.EditTeam).
+			m.Combo("").Patch(reqToken(), reqOrgOwnership(), bind(api.EditTeamOption{}), org.EditTeam).
 				Delete(reqToken(), reqOrgOwnership(), org.DeleteTeam)
+			m.Group("", func() {
+				m.Get("", org.GetTeam)
+				m.Group("/members", func() {
+					m.Get("", reqOrgMembership(), org.GetTeamMembers)
+					m.Combo("/{username}").Get(reqOrgMembership(), org.GetTeamMember)
+				})
+				m.Group("/repos", func() {
+					m.Get("", org.GetTeamRepos)
+					m.Combo("/{org}/{reponame}").Get(org.GetTeamRepo)
+				})
+				m.Get("/activities/feeds", org.ListTeamActivityFeeds)
+			}, reqTeamReadAccess())
 			m.Group("/members", func() {
-				m.Get("", reqToken(), org.GetTeamMembers)
 				m.Combo("/{username}").
-					Get(reqToken(), org.GetTeamMember).
 					Put(reqToken(), reqOrgOwnership(), org.AddTeamMember).
 					Delete(reqToken(), reqOrgOwnership(), org.RemoveTeamMember)
 			})
 			m.Group("/repos", func() {
-				m.Get("", reqToken(), org.GetTeamRepos)
 				m.Combo("/{org}/{reponame}").
-					Put(reqToken(), org.AddTeamRepository).
-					Delete(reqToken(), org.RemoveTeamRepository).
-					Get(reqToken(), org.GetTeamRepo)
+					Put(reqToken(), reqTeamMembership(), org.AddTeamRepository).
+					Delete(reqToken(), reqTeamMembership(), org.RemoveTeamRepository)
 			})
-			m.Get("/activities/feeds", org.ListTeamActivityFeeds)
-		}, tokenRequiresScopes(auth_model.AccessTokenScopeCategoryOrganization), orgAssignment(false, true), reqToken(), reqTeamMembership(), checkTokenPublicOnly())
+		}, tokenRequiresScopes(auth_model.AccessTokenScopeCategoryOrganization), orgAssignment(false, true), reqToken(), checkTokenPublicOnly())
 
 		m.Group("/admin", func() {
 			m.Group("/cron", func() {