feat: add initial

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

todos/SQ-005-wal-segment-reader.md

@@ -0,0 +1,37 @@
+# SQ-005: WAL Segment Reader
+
+**Status:** `[ ] TODO`
+**Blocked by:** SQ-004
+**Priority:** High
+
+## Description
+
+Implement the WAL segment reader that reads messages from segment files, supporting seek-to-offset and forward scanning.
+
+## Files to Create/Modify
+
+- `crates/sq-storage/src/wal/reader.rs` - WalReader with open, read_from, iterator
+
+## WalReader API
+
+```rust
+pub struct WalReader<F: FileSystem> {
+    fs: Arc<F>,
+}
+
+impl<F: FileSystem> WalReader<F> {
+    pub fn new(fs: Arc<F>) -> Self;
+    pub async fn read_segment(&self, path: &Path) -> Result<Vec<Message>>;
+    pub async fn read_from_offset(&self, path: &Path, offset: u64) -> Result<Vec<Message>>;
+    pub async fn read_segment_header(&self, path: &Path) -> Result<SegmentHeader>;
+}
+```
+
+## Acceptance Criteria (using InMemoryFileSystem)
+
+- [ ] Write N messages with writer, read all back with reader, verify equality
+- [ ] Read from a specific offset in the middle of a segment
+- [ ] Corrupted record mid-segment: reader returns error for that record, can report partial results
+- [ ] Empty segment (header only): reader yields zero messages
+- [ ] Invalid magic bytes: reader returns descriptive error
+- [ ] Truncated record at end of segment (partial write): reader stops cleanly at last complete record