story-kit: merge 277 - bot uses configured display_name

Adds system_prompt parameter to chat_stream so the Matrix bot
passes "Your name is {name}" to Claude Code. Reads display_name
from bot.toml config. Resolved conflicts by integrating bot_name
into master's permission-handling code structure.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/src/llm/providers/claude_code.rs

@@ -42,6 +42,7 @@ impl ClaudeCodeProvider {
         user_message: &str,
         project_root: &str,
         session_id: Option<&str>,
+        system_prompt: Option<&str>,
         cancel_rx: &mut watch::Receiver<bool>,
         mut on_token: F,
         mut on_thinking: T,
@@ -55,6 +56,7 @@ impl ClaudeCodeProvider {
         let message = user_message.to_string();
         let cwd = project_root.to_string();
         let resume_id = session_id.map(|s| s.to_string());
+        let sys_prompt = system_prompt.map(|s| s.to_string());
         let cancelled = Arc::new(AtomicBool::new(false));
         let cancelled_clone = cancelled.clone();
 
@@ -79,6 +81,7 @@ impl ClaudeCodeProvider {
                 &message,
                 &cwd,
                 resume_id.as_deref(),
+                sys_prompt.as_deref(),
                 cancelled,
                 token_tx,
                 thinking_tx,
@@ -147,6 +150,7 @@ fn run_pty_session(
     user_message: &str,
     cwd: &str,
     resume_session_id: Option<&str>,
+    system_prompt: Option<&str>,
     cancelled: Arc<AtomicBool>,
     token_tx: tokio::sync::mpsc::UnboundedSender<String>,
     thinking_tx: tokio::sync::mpsc::UnboundedSender<String>,
@@ -185,6 +189,10 @@ fn run_pty_session(
     // a tool requires user approval, instead of using PTY stdin/stdout.
     cmd.arg("--permission-prompt-tool");
     cmd.arg("mcp__story-kit__prompt_permission");
+    if let Some(sys) = system_prompt {
+        cmd.arg("--system");
+        cmd.arg(sys);
+    }
     cmd.cwd(cwd);
     // Keep TERM reasonable but disable color
     cmd.env("NO_COLOR", "1");