feat(migrations): add repository migration from bitbucket.org (#38607)

Adds migration from bitbucket.org as the Cloud variant of the Bitbucket
entry, in the web UI and via `POST /repos/migrate` with
`service=bitbucket`. It migrates the repository and pull requests with
their comments and reviews. Bitbucket Cloud has no releases, and
Atlassian removed its issues and wikis on 2026-08-20
(https://community.atlassian.com/forums/Bitbucket-articles/Announcing-sunset-of-Bitbucket-Issues-and-Wikis/ba-p/3193882).

- Private repositories need an API or access token, which also raises
the rate limit.
- Rate-limited requests back off and retry, Bitbucket sends no
`Retry-After`.
- Tests replay recorded responses, set `BITBUCKET_READ_TOKEN` to
re-record.

Co-authored-by: silverwind <me@silverwind.io>

modules/structs/repo.go

@@ -359,6 +359,7 @@ const (
 	CodeCommitService                            // 9 codecommit service
 	BitbucketServerService                       // 10 bitbucket server (data center) service
 	ForgejoService                               // 11 forgejo service
+	BitbucketService                             // 12 bitbucket.org service
 )
 
 // Name represents the service type's name
@@ -390,6 +391,8 @@ func (gt GitServiceType) Title() string {
 		return "Bitbucket Server"
 	case ForgejoService:
 		return "Forgejo"
+	case BitbucketService:
+		return "Bitbucket"
 	case PlainGitService:
 		return "Git"
 	}
@@ -399,21 +402,12 @@ func (gt GitServiceType) Title() string {
 // Variants returns the hosting options of gt's provider, which share one entry on the migrate page
 func (gt GitServiceType) Variants() []GitServiceType {
 	switch gt {
-	case BitbucketServerService:
-		return []GitServiceType{BitbucketServerService}
+	case BitbucketService, BitbucketServerService:
+		return []GitServiceType{BitbucketService, BitbucketServerService}
 	}
 	return nil
 }
 
-// ProviderTitle returns the title of gt's entry on the migrate page
-func (gt GitServiceType) ProviderTitle() string {
-	switch gt {
-	case BitbucketServerService:
-		return "Bitbucket"
-	}
-	return gt.Title()
-}
-
 // MigrateRepoOptions options for migrating repository's
 // this is used to interact with api v1
 type MigrateRepoOptions struct {
@@ -426,7 +420,7 @@ type MigrateRepoOptions struct {
 	// required: true
 	RepoName string `json:"repo_name" binding:"Required;AlphaDashDot;MaxSize(100)"`
 
-	// enum: ["git","github","gitea","gitlab","gogs","onedev","gitbucket","codebase","codecommit","bitbucketserver","forgejo"]
+	// enum: ["git","github","gitea","gitlab","gogs","onedev","gitbucket","codebase","codecommit","bitbucketserver","forgejo","bitbucket"]
 	Service      string `json:"service"`
 	AuthUsername string `json:"auth_username"`
 	AuthPassword string `json:"auth_password"`
@@ -464,6 +458,7 @@ var SupportedFullGitService = []GitServiceType{
 	GithubService,
 	GitlabService,
 	GiteaService,
+	BitbucketService,
 	ForgejoService,
 	GogsService,
 	OneDevService,