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/STARLARK-REFERENCE.md

@@ -429,3 +429,30 @@ def on_run(ctx):
 
     return {"advance": True, "data": {"needs_review": False}}
 ```
+
+---
+
+## `forms` Module (v0.9.5)
+
+**Permission:** `forms.validate`
+
+Validates form data against a typed form template.
+
+### `forms.validate(template, data)`
+
+Validates `data` (a dict) against a `template` (a dict matching the TypedFormTemplate schema).
+
+Returns a dict: `{"valid": True/False, "errors": [{"key": "...", "message": "..."}]}`.
+
+```python
+result = forms.validate(
+    {"fields": [{"key": "name", "type": "text", "label": "Name", "required": True}]},
+    {"name": "Alice"},
+)
+# result["valid"] == True
+# result["errors"] == []
+```
+
+Field types: `text`, `email`, `select`, `number`, `date`, `textarea`, `checkbox`, `file`.
+
+Supports: required checks, min/max length, pattern (regex), number range, date range, select option whitelist, conditional visibility (`condition.when`/`op`/`value`).