Add task queue with dedup and concurrency control

- Tasks keyed by {taskType}-{repo}-{issue} for deduplication
- Duplicate requests (pending or running) are dropped
- Configurable concurrency via QUEUE_CONCURRENCY env (default 2)
- Workspace names now {taskType}-{repo}-{issue} for observability
- GET /queue endpoint shows pending/running tasks
- All handlers route through the queue instead of calling Coder directly

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/handlers/issue-label.ts

@@ -1,7 +1,6 @@
 import type { Context } from "hono";
 import type { IssueEvent, TaskRequest } from "../types.js";
-import type { CoderClient } from "../services/coder.js";
-import type { GiteaClient } from "../services/gitea.js";
+import type { TaskQueue } from "../queue.js";
 import type { Config } from "../config.js";
 
 const LABEL_TO_TASK: Record<string, string> = {
@@ -19,7 +18,7 @@ const REVIEW_TASKS = new Set(["test"]);
  *
  * Replaces: issue-stage-transition.json
  */
-export function issueLabel(config: Config, coder: CoderClient, gitea: GiteaClient) {
+export function issueLabel(config: Config, queue: TaskQueue) {
   return async (c: Context) => {
     const event = await c.req.json<IssueEvent>();
 
@@ -55,18 +54,11 @@ export function issueLabel(config: Config, coder: CoderClient, gitea: GiteaClien
       giteaToken,
     };
 
-    console.log(`[issue-label] #${task.issueNumber} → ${taskType}`);
+    const queued = queue.enqueue(task, {
+      useReviewAccount: false,
+      body: `🤖 SDLC stage transition: **${taskType}** — workspace queued.`,
+    });
 
-    const workspace = await coder.createWorkspace(task);
-    console.log(`[issue-label] workspace created: ${workspace.name}`);
-
-    await gitea.commentOnIssue(
-      org,
-      repo,
-      event.issue.number,
-      `🤖 SDLC stage transition: **${taskType}** — workspace created.`,
-    );
-
-    return c.json({ ok: true, workspace: workspace.name });
+    return c.json({ ok: true, queued });
   };
 }