Removes private import from custom-hook.

The `custom-hook` example was importing `ComponentAccessor` directly, it should be importing from the public entry point.

src/demo/hooks/custom-hook.ts

@@ -1,5 +1,4 @@
-import { HydroActiveComponent, defineSignalComponent } from 'hydroactive';
-import { ComponentAccessor } from 'hydroactive/component-accessor.js';
+import { ComponentAccessor, HydroActiveComponent, defineSignalComponent } from 'hydroactive';
 import { bind } from 'hydroactive/signal-accessors.js';
 import { Signal, signal } from 'hydroactive/signals.js';