docs: add npm run update script and recommend npm ci (#259)

Users running npm install get a dirty lockfile that blocks git pull.
Add an update script that handles the reset+pull+install+build cycle,
and document npm ci as the recommended install method.

Written by Cameron ◯ Letta Code

"Simplicity is the ultimate sophistication." -- Leonardo da Vinci

docs/getting-started.md

@@ -16,9 +16,11 @@ Get LettaBot running in 5 minutes.
 ```bash
 git clone https://github.com/letta-ai/lettabot.git
 cd lettabot
-npm install
+npm ci
 ```
 
+> **Note:** Always use `npm ci` (not `npm install`) to avoid modifying the lockfile, which would block future `git pull` updates.
+
 ### 2. Create a Telegram Bot
 
 1. Open Telegram and message [@BotFather](https://t.me/BotFather)
@@ -95,6 +97,16 @@ To limit who can use your bot, set `ALLOWED_USERS`:
 ALLOWED_USERS=123456789,987654321
 ```
 
+## Updating
+
+Pull the latest changes and rebuild:
+
+```bash
+npm run update
+```
+
+This resets the lockfile, pulls from git, installs dependencies, and rebuilds. If you've modified source files locally, stash them first with `git stash`.
+
 ## Next Steps
 
 - [Commands Reference](./commands.md) - Learn all bot commands