feat(forge): pluggable forge abstraction + GitLab and Gitea/Forgejo/Codeberg (#1913)

* refactor(forge): forge-neutral foundation (GitHub-only)

Decouple git-hosting from GitHub behind a neutral abstraction (issue #1616), GitHub-only for now; existing GitHub behaviour is unchanged.

- Forge manifest, neutral ForgeService contract, forge registry + resolver, and a client forge-module registry.
- GitHub code renamed to the neutral shape; PR/Issue attachment wording preserved.
- forge.search.response enums parse tolerantly (unknown kind/auth state degrade instead of breaking the client).
- createPullRequest reports typed CLI/auth errors instead of a generic message.
- forge-resolver host/remote caches are LRU-bounded.
- Forge host trust is explicit: only a known cloud host or a CLI-authenticated host is ever talked to; an unauthenticated GitHub Enterprise host fails resolution instead of routing to github.com.
- Docs: forge-providers guide, glossary and i18n forge-copy conventions, architecture and rpc-namespacing terminology.
- Vitest React Native mocks (unistyles, svg, linking, lucide) consolidated into shared aliased test-stubs.

* feat(forge): GitLab adapter, forge-aware UI, pipelines and approvals

GitLab adapter over the glab CLI on the neutral contracts: MR status, forge-aware UI, pipeline tree, and N-of-M approvals.

- threadIsResolved is part of the neutral timeline item.
- Pipeline load failures show an error instead of an empty section.
- Manual pipeline jobs render as pending.
- Fork/detached MR head pipelines are fetched by MR iid (glab ci get --merge-request).

* feat(forge): Gitea family adapter (Gitea, Forgejo, Codeberg)

One adapter over the tea CLI serving Gitea, Forgejo, and Codeberg on the neutral contracts.

- CI status aggregates commit statuses and Actions runs together.
- Gitea's terminal "warning" state maps to failure on server and client.
- Gitea Actions check details are reachable from the PR pane by workflowRunId.

* refactor(forge): localize compatibility handling

* test(forge): expect normalized GitLab facts

---------

Co-authored-by: Mohamed Boudra <boudra.moha@gmail.com>

packages/server/src/services/gitlab-facts.ts

@@ -0,0 +1,49 @@
+import type { ForgeSpecificStatusFacts } from "./forge-service.js";
+
+export interface GitLabStatusFacts {
+  detailedMergeStatus: string | null;
+  /**
+   * Legacy `merge_status` (pre-15.6 GitLab), used as the direct-merge readiness
+   * signal when `detailedMergeStatus` is absent on older self-managed instances.
+   */
+  mergeStatus: string | null;
+  hasConflicts: boolean;
+  blockingDiscussionsResolved: boolean;
+  approvalsRequired: number;
+  approvalsGiven: number;
+  pipelineStatus: string | null;
+  /**
+   * Id of the MR's head pipeline, used to fetch the full pipeline (stages ->
+   * jobs) on demand. Null when the MR has no pipeline yet.
+   */
+  pipelineId: number | null;
+  pipelineUrl: string | null;
+  mergeWhenPipelineSucceeds: boolean;
+}
+
+// Client-side twin: packages/app/src/git/forges/gitlab.ts
+// (GITLAB_ACTIVE_PIPELINE_STATUSES / isPipelineActiveStatus). Duplicated because
+// the app can't depend on the server package; keep the two lists in sync by hand
+// if GitLab adds a new active pipeline status.
+export const GITLAB_ACTIVE_PIPELINE_STATUSES = [
+  "created",
+  "waiting_for_resource",
+  "preparing",
+  "pending",
+  "running",
+  "scheduled",
+] as const;
+
+export type GitLabActivePipelineStatus = (typeof GITLAB_ACTIVE_PIPELINE_STATUSES)[number];
+
+export const GITLAB_ACTIVE_PIPELINE_STATUS_SET = new Set<string>(GITLAB_ACTIVE_PIPELINE_STATUSES);
+
+export type GitLabForgeSpecificStatusFacts = ForgeSpecificStatusFacts & {
+  forge: "gitlab";
+} & GitLabStatusFacts;
+
+export function isGitLabStatusFacts(
+  facts: ForgeSpecificStatusFacts | null | undefined,
+): facts is GitLabForgeSpecificStatusFacts {
+  return facts?.forge === "gitlab";
+}