Document the CodeIgniter bootstrap and SQLite-affinity limitation

Author: paulbalandan

README.md

@@ -13,6 +13,7 @@ This PHPStan extension provides type inference support and rules for `CodeIgnite
 
 * [Rules](docs/rules.md)
 * [Type inference](docs/type-inference.md)
+* [Upgrading from 1.x to 2.x](docs/upgrading.md)
 
 ## Installation
 
@@ -35,6 +36,23 @@ includes:
 ```
 </details>
 
+## Bootstrapping CodeIgniter
+
+This extension boots CodeIgniter during analysis so it can read your configuration, services, and database
+schema. Point PHPStan at a bootstrap file that loads the framework. CodeIgniter's own test bootstrap works
+out of the box:
+
+```yml
+parameters:
+    bootstrapFiles:
+        - vendor/codeigniter4/framework/system/Test/bootstrap.php
+```
+
+The Model and Entity type inference additionally materializes your schema by running your migrations against
+a temporary SQLite database, so the `sqlite3` PHP extension is required (it is declared in this package's
+`composer.json`). The schema is cached under the working directory's `tmp` folder by default. See the
+[type inference docs](docs/type-inference.md) for how to point it at a specific namespace.
+
 ## Contributing
 
 Any contributions are welcome.

docs/upgrading.md

@@ -121,6 +121,10 @@ Both are optional. The defaults work for a typical application.
 
 ## Known limitations
 
+- **Column types reflect SQLite affinity, not your production database.** The schema is materialized in
+  SQLite, so a column's type follows SQLite's column affinity rather than your MySQL or Postgres type. A
+  `BOOLEAN` column reads back as `int`, `DECIMAL` as `string`, and `ENUM`/`SET` as `string`. Add a `$casts`
+  entry (for example `'is_active' => 'boolean'`) when you want the precise PHP type.
 - **Models that set `$table` in the constructor are not mapped.** The entity-to-table bridge reads `$table`
   from the model's default property value. A model that assigns `$this->table` inside its constructor is not
   resolved, so its entity's non-cast properties fall back to `mixed`.