fix installer for externally managed Python

docs/quick-start.md

@@ -32,7 +32,7 @@ On Windows PowerShell:
 irm https://raw.githubusercontent.com/HKUDS/nanobot/main/scripts/install.ps1 | iex
 ```
 
-The default command installs or upgrades `nanobot-ai` from PyPI, then starts `nanobot onboard --wizard`. If you finish the wizard and save the config, skip the manual initialize/configure steps and go straight to [Check the Setup](#4-check-the-setup).
+The default command installs or upgrades `nanobot-ai` from PyPI, then starts `nanobot onboard --wizard`. It avoids system-wide pip installs by using an active virtual environment, `uv`, `pipx`, or a managed venv under `~/.nanobot/venv`. If you finish the wizard and save the config, skip the manual initialize/configure steps and go straight to [Check the Setup](#4-check-the-setup).
 
 To preview the plan without changing your environment, pass `--dry-run`; combine it with `--dev` when you want to preview the main-branch install.
 
@@ -72,6 +72,8 @@ python -m pip install nanobot-ai
 nanobot --version
 ```
 
+Use pip only inside an environment you control. If pip reports `externally-managed-environment` on macOS or Linux, use the one-command installer, `uv tool install nanobot-ai`, `pipx install nanobot-ai`, or create a virtual environment first.
+
 **Latest source checkout:**
 
 ```bash
@@ -286,6 +288,8 @@ python -m pip install -U nanobot-ai
 nanobot --version
 ```
 
+If pip reports `externally-managed-environment`, upgrade with the same isolated method you used to install nanobot, such as `uv tool upgrade nanobot-ai`, `pipx upgrade nanobot-ai`, or the managed venv created by the one-command installer.
+
 **uv:**
 
 ```bash
@@ -293,6 +297,13 @@ uv tool upgrade nanobot-ai
 nanobot --version
 ```
 
+**pipx:**
+
+```bash
+pipx upgrade nanobot-ai
+nanobot --version
+```
+
 **Source checkout:**
 
 ```bash