chore(cli): remove agent-rush command and de-brand whoami

The AGENTRUSH game has ended. Remove the agent-rush add/search
subcommands from both CLIs, change the whoami output to
'Your user_id:  <default_user_id>', drop the agent_rush config
key handling, and update the CLI docs page accordingly.

Bumps mem0-cli to 0.2.10 and @mem0/cli to 0.2.11.

cli/python/pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "mem0-cli"
-version = "0.2.9"
+version = "0.2.10"
 description = "The official CLI for mem0 — the memory layer for AI agents"
 readme = "README.md"
 license = "Apache-2.0"