docs: add task files for deferred safety/enhancement work

- remote-conversation-loading.md — implement list/load for RemoteBackend
- settings-error-display.md — wire validation errors to footer
- dead-code-cleanup.md — remove allow(dead_code), Letta aliases, unused imports
- numeric-cast-safety.md — add saturating cast helpers

docs/tasks/remote-conversation-loading.md

@@ -0,0 +1,47 @@
+# Task: Implement Remote Conversation Listing and Loading
+
+**Priority:** Medium
+**Effort:** 2-4 hours
+**Files:** `src/backend/remote.rs`
+
+## Context
+
+The `RemoteBackend` has two stub methods:
+
+```rust
+async fn list_conversations(&self, _agent_id: &str) -> Result<Vec<ConversationInfo>> {
+    Ok(Vec::new()) // TODO
+}
+
+async fn load_conversation(&self, _conversation_id: &str) -> Result<Vec<ConversationMessage>> {
+    anyhow::bail!("Remote conversation loading not yet implemented")
+}
+```
+
+Anyone using the remote backend gets empty conversation history and an error on load.
+
+## Requirements
+
+1. **list_conversations** — Implement `GET /v1/agents/:id/conversations`:
+   - Deserialize response into `Vec<ConversationInfo>`
+   - Handle pagination if the API supports it
+   - Return empty vec on 404 (agent has no conversations yet)
+
+2. **load_conversation** — Implement `GET /v1/conversations/:id/messages`:
+   - Deserialize response into `Vec<ConversationMessage>`
+   - Handle SSE streaming if the API streams messages
+   - Return clear error if conversation doesn't exist
+
+## API Design Notes
+
+- Check `src/server/conversation.rs` for the server-side endpoints
+- The server may already implement these — just wire the client
+- Use the existing `auth_req()` pattern for bearer token injection
+- Follow the `send()` method's SSE parsing pattern if streaming is needed
+
+## Acceptance Criteria
+
+- [ ] `list_conversations` returns real data from the server
+- [ ] `load_conversation` returns full message history
+- [ ] Both methods handle errors gracefully (network, 404, auth)
+- [ ] Tests cover happy path and error cases