feat: implement dynamic bot list with runtime add/remove support

Adds a new BotManager class that maintains a mutable list of active bots, allowing bots to be added or removed at runtime without restarting the application. Includes thread-safe operations for concurrent access and a new API endpoint to query the current bot roster.

Makefile

@@ -1,5 +1,6 @@
 ENV=./.venv/bin/activate
 PYTHON=./.venv/bin/python
+BIN=./.venv/bin
 all: ensure_env format build install test
 
 format:
@@ -17,7 +18,7 @@ install:
 	$(PYTHON) -m pip install -e .
 
 run:
-	$(PYTHON) -m ragnar.run
+	$(BIN)/ragnar.run
 
 test: 
 	$(PYTHON) -m unittest ragnar.tests