feat: bot alias reservation + BOT_API.md documentation

- Aliases ending with Bot/bot/_bot reserved for registered bots only
- Non-bot users get clear error directing to /v1/bot/register
- Bot registration auto-creates alias (@name_bot suffix)
- BOT_API.md: full developer guide with endpoints, examples, echo bot
- LLM_HELP.md: expanded bot section with update types + Python example

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

warzone/crates/warzone-server/src/routes/bot.rs

@@ -100,12 +100,25 @@ async fn register_bot(
         &token[..token.len().min(20)]
     );
 
+    // Auto-register bot alias (name must end with Bot or _bot)
+    let bot_alias = if req.name.ends_with("Bot") || req.name.ends_with("_bot") || req.name.ends_with("bot") {
+        req.name.to_lowercase()
+    } else {
+        format!("{}_bot", req.name.to_lowercase())
+    };
+    let alias_key = format!("a:{}", bot_alias);
+    let _ = state.db.aliases.insert(alias_key.as_bytes(), fp.as_bytes());
+    let fp_key = format!("fp:{}", fp);
+    let _ = state.db.aliases.insert(fp_key.as_bytes(), bot_alias.as_bytes());
+    tracing::info!("Bot alias @{} registered for {}", bot_alias, fp);
+
     Ok(Json(serde_json::json!({
         "ok": true,
         "result": {
             "token": token,
             "name": req.name,
             "fingerprint": fp,
+            "alias": format!("@{}", bot_alias),
         }
     })))
 }