feat: add in-memory job store

app/store.py

@@ -0,0 +1,18 @@
+from app.models import Job, JobStatus
+
+
+class JobStore:
+    def __init__(self) -> None:
+        self._jobs: dict[str, Job] = {}
+
+    def add(self, job: Job) -> None:
+        self._jobs[job.id] = job
+
+    def get(self, job_id: str) -> Job | None:
+        return self._jobs.get(job_id)
+
+    def list_all(self) -> list[Job]:
+        return list(self._jobs.values())
+
+    def list_by_status(self, status: JobStatus) -> list[Job]:
+        return [job for job in self._jobs.values() if job.status == status]