feat: conversation persistence, input expansion, overlay UX

- ConversationStore (JSONL + JSON metadata) wired through Backend trait,
  SessionManager, and TUI (/new, /resume, /convos commands)
- Dynamic input box: grows with content, caps at 40% terminal height,
  scrolls internally. Shift+Enter / Ctrl+J for newlines.
- Slash command autocomplete popup (filters live as you type /)
- Conversation picker overlay for /resume (modal, arrow select, Enter switch)
- Splash bloom animation, color_support module, system prompt builder
- Fixed 8 pre-existing test failures (95/95 pass)
- Archived superseded task docs, consolidated planning references

src/api/models.rs

@@ -38,6 +38,11 @@ pub struct LlmConfig {
     /// Configurable per-agent; 0 disables tools entirely.
     #[serde(default = "default_max_tool_rounds")]
     pub max_tool_rounds: u32,
+    /// Milliseconds to wait between tool rounds to avoid rate-limit cascades.
+    /// The follow-up LLM call after a tool executes can trigger rate limits
+    /// if it arrives too quickly. Default 500ms.
+    #[serde(default = "default_inter_round_delay")]
+    pub inter_round_delay_ms: u64,
 }
 
 fn default_context_window() -> u32 {
@@ -48,6 +53,10 @@ fn default_max_tool_rounds() -> u32 {
     10
 }
 
+fn default_inter_round_delay() -> u64 {
+    500
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct MemoryConfig {
     pub git_enabled: bool,