Docs: say plainly that only the bot is open source; the dashboard and API are proprietary

- README, license section and architecture no longer point to the dashboard repositories
- schema.sql is the schema for contributors; database changes only need schema.sql and a note in the PR
- self-hosting: settings without a dashboard (SQL for security thresholds, beta settings, opted-in servers)
- beta features, deployment and troubleshooting reworded for people who don't have the dashboard

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>

CONTRIBUTING.md

@@ -17,7 +17,7 @@ If you find a way to get around a permission check, make the bot act for someone
 
 1. **Open an issue for anything big**: a new module, a change to how permissions or security work, a change to the database. It saves you from writing something that can't be merged.
 2. Read [Architecture](docs/architecture.md) so you know the layers, and the [Development guide](docs/development.md) for the recipe that matches your change.
-3. For anything that touches the database, read [Database](docs/database.md#changing-the-schema). Tables are shared with the dashboard, so a change has to be compatible with an older bot for a short while.
+3. For anything that touches the database, read [Database](docs/database.md#changing-the-schema). A schema change has to keep a bot that is one version behind working for a short while.
 
 ## Making the change
 
@@ -45,7 +45,7 @@ These are the things a reviewer will check first. The reasons are in the [Develo
 - **No SQL outside repos.** Always use query parameters (`$1`), never string formatting.
 - **A module that acts on a server starts off.** An admin turns it on.
 - **Escape user text and set `AllowedMentions`** so a message can't ping people.
-- **Validate everything that comes from users or from the dashboard**: options, custom IDs, command payloads.
+- **Validate everything that comes from users or from other programs writing to the database**: options, custom IDs, command payloads.
 - **No secrets** in code, logs, tests or commit messages.
 
 ## Commit messages and pull requests