feat: add initial

Signed-off-by: kjuulh <contact@kjuulh.io>

todos/SQ-016-object-store-shipping.md

@@ -0,0 +1,45 @@
+# SQ-016: Object Store Shipping
+
+**Status:** `[ ] TODO`
+**Blocked by:** SQ-007
+**Priority:** Medium
+
+## Description
+
+Background process that ships closed WAL segments to S3-compatible object storage for long-term durability.
+
+## Files to Create/Modify
+
+- `crates/sq-storage/src/object_store/mod.rs` - ObjectStore trait + S3 impl + Noop impl
+- `crates/sq-storage/src/object_store/shipper.rs` - SegmentShipper as notmad::Component
+- `crates/sq-storage/src/object_store/layout.rs` - S3 key naming convention
+
+## ObjectStore Trait
+
+```rust
+pub trait ObjectStore: Send + Sync {
+    async fn put(&self, key: &str, data: Vec<u8>) -> Result<()>;
+    async fn get(&self, key: &str) -> Result<Vec<u8>>;
+    async fn list(&self, prefix: &str) -> Result<Vec<String>>;
+    async fn delete(&self, key: &str) -> Result<()>;
+}
+```
+
+## S3 Key Layout
+
+`{cluster_id}/{topic}/{partition}/{base_offset}-{end_offset}.sqseg`
+
+## Acceptance Criteria
+
+- [ ] Closed segment is detected and uploaded to object store
+- [ ] S3 key matches expected layout
+- [ ] Noop object store works for testing (stores in memory)
+- [ ] Upload failure: segment stays local, retried on next cycle
+- [ ] Successful upload is recorded (segment marked as "shipped")
+- [ ] Uses zstd compression before upload
+
+## Notes
+
+- Uses `object_store` crate with AWS S3 features (same as nostore)
+- Shipper runs as a notmad::Component in the background
+- Poll interval: every 5 seconds check for closed segments