feat: add initial

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

todos/SQ-014-sdk-producer.md

@@ -0,0 +1,42 @@
+# SQ-014: SDK Producer
+
+**Status:** `[ ] TODO`
+**Blocked by:** SQ-010
+**Priority:** Medium
+
+## Description
+
+Ergonomic Rust producer client in sq-sdk. Handles connection management, batching, and retry logic.
+
+## Files to Create/Modify
+
+- `crates/sq-sdk/src/lib.rs` - re-exports
+- `crates/sq-sdk/src/connection.rs` - gRPC channel management
+- `crates/sq-sdk/src/producer.rs` - Producer with batching, linger timer, retry
+- `crates/sq-sdk/src/error.rs` - SqError type
+
+## Producer API
+
+```rust
+pub struct ProducerConfig {
+    pub server_addresses: Vec<String>,
+    pub default_ack_mode: AckMode,
+    pub max_retries: u32,
+    pub retry_backoff_ms: u64,
+}
+
+pub struct Producer { /* ... */ }
+
+impl Producer {
+    pub async fn connect(config: ProducerConfig) -> Result<Self, SqError>;
+    pub async fn send(&self, topic: &str, key: Option<&[u8]>, value: &[u8]) -> Result<SendResult, SqError>;
+    pub async fn send_batch(&self, messages: Vec<ProducerMessage>) -> Result<Vec<SendResult>, SqError>;
+}
+```
+
+## Acceptance Criteria
+
+- [ ] Producer connects to running server, sends message, gets offset back
+- [ ] Send batch: all messages get sequential offsets
+- [ ] Connection failure: returns appropriate error
+- [ ] Multiple server addresses: round-robin or failover