Feat v0.9.5 typed forms SDK primitive

Extract typed form system from models/workflow.go into standalone
server/forms/ package. Any package can now declare and validate
forms, not just workflow stages.

- New server/forms/ package (types + validation + condition evaluator)
- REST POST /api/v1/forms/validate endpoint
- Starlark forms.validate(template, data) module
- Frontend sw.forms.render(), .validate(), .validateRemote()
- Manifest form_template accepted at package level
- 16 new tests (12 forms + 4 Starlark module)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/FRONTEND-JS-GUIDE.md

@@ -248,6 +248,44 @@ Every surface uses one of three patterns:
 The shell provides the home link, notification bell, and user menu
 on every surface for free.
 
+## `sw.forms` — Typed Forms (v0.9.5)
+
+Any extension can render and validate typed forms using the `sw.forms` module.
+
+### `sw.forms.render(container, template, opts)`
+
+Renders a typed form into a DOM container. Supports flat forms and progressive
+multi-step forms (fieldsets). Returns a control handle.
+
+```js
+const handle = sw.forms.render(document.getElementById('my-form'), template, {
+    values: { name: 'prefilled' },
+    onSubmit: (data) => { console.log('submitted', data); },
+});
+
+// Programmatic access
+const data = handle.getData();
+handle.setErrors([{ key: 'name', message: 'Name is taken' }]);
+handle.destroy();
+```
+
+### `sw.forms.validate(template, data)`
+
+Client-side validation (no network call). Returns `{ valid, errors }`.
+
+```js
+const { valid, errors } = sw.forms.validate(template, { name: '' });
+// valid === false, errors === [{ key: 'name', message: 'Name is required' }]
+```
+
+### `sw.forms.validateRemote(template, data)`
+
+Server-side validation via `POST /api/v1/forms/validate`. Returns a Promise.
+
+```js
+const result = await sw.forms.validateRemote(template, data);
+```
+
 ## Extension CSS contract
 
 Extensions must prefix all CSS classes with `.ext-{slug}-` to avoid