feat(memory): add session_id isolation to Memory trait (#530)

* feat(memory): add session_id isolation to Memory trait

Add optional session_id parameter to store(), recall(), and list()
methods across the Memory trait and all four backends (sqlite, markdown,
lucid, none). This enables per-session memory isolation so different
agent sessions cannot cross-read each other's stored memories.

Changes:
- traits.rs: Add session_id: Option<&str> to store/recall/list
- sqlite.rs: Schema migration (ALTER TABLE ADD COLUMN session_id),
  index, persist/filter by session_id in all query paths
- markdown.rs, lucid.rs, none.rs: Updated signatures
- All callers pass None for backward compatibility
- 5 new tests: session-filtered recall, cross-session isolation,
  session-filtered list, no-filter returns all, migration idempotency

Closes #518

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

* fix(channels): fix discord _channel_id typo and lark missing reply_to

Pre-existing compilation errors on main after reply_to was added to
ChannelMessage: discord.rs used _channel_id (underscore prefix) but
referenced channel_id, and lark.rs was missing the reply_to field.

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

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

src/channels/mod.rs

@@ -72,7 +72,7 @@ fn conversation_memory_key(msg: &traits::ChannelMessage) -> String {
 async fn build_memory_context(mem: &dyn Memory, user_msg: &str) -> String {
     let mut context = String::new();
 
-    if let Ok(entries) = mem.recall(user_msg, 5).await {
+    if let Ok(entries) = mem.recall(user_msg, 5, None).await {
         if !entries.is_empty() {
             context.push_str("[Memory context]\n");
             for entry in &entries {
@@ -158,6 +158,7 @@ async fn process_channel_message(ctx: Arc<ChannelRuntimeContext>, msg: traits::C
                 &autosave_key,
                 &msg.content,
                 crate::memory::MemoryCategory::Conversation,
+                None,
             )
             .await;
     }
@@ -1260,6 +1261,7 @@ mod tests {
             _key: &str,
             _content: &str,
             _category: crate::memory::MemoryCategory,
+            _session_id: Option<&str>,
         ) -> anyhow::Result<()> {
             Ok(())
         }
@@ -1268,6 +1270,7 @@ mod tests {
             &self,
             _query: &str,
             _limit: usize,
+            _session_id: Option<&str>,
         ) -> anyhow::Result<Vec<crate::memory::MemoryEntry>> {
             Ok(Vec::new())
         }
@@ -1279,6 +1282,7 @@ mod tests {
         async fn list(
             &self,
             _category: Option<&crate::memory::MemoryCategory>,
+            _session_id: Option<&str>,
         ) -> anyhow::Result<Vec<crate::memory::MemoryEntry>> {
             Ok(Vec::new())
         }
@@ -1636,6 +1640,7 @@ mod tests {
             &conversation_memory_key(&msg1),
             &msg1.content,
             MemoryCategory::Conversation,
+            None,
         )
         .await
         .unwrap();
@@ -1643,13 +1648,14 @@ mod tests {
             &conversation_memory_key(&msg2),
             &msg2.content,
             MemoryCategory::Conversation,
+            None,
         )
         .await
         .unwrap();
 
         assert_eq!(mem.count().await.unwrap(), 2);
 
-        let recalled = mem.recall("45", 5).await.unwrap();
+        let recalled = mem.recall("45", 5, None).await.unwrap();
         assert!(recalled.iter().any(|entry| entry.content.contains("45")));
     }
 
@@ -1657,7 +1663,7 @@ mod tests {
     async fn build_memory_context_includes_recalled_entries() {
         let tmp = TempDir::new().unwrap();
         let mem = SqliteMemory::new(tmp.path()).unwrap();
-        mem.store("age_fact", "Age is 45", MemoryCategory::Conversation)
+        mem.store("age_fact", "Age is 45", MemoryCategory::Conversation, None)
             .await
             .unwrap();