Feature Policies API + Invitations Policies (#375)

- Added Feature Policy API: a declarative system to enable/disable/modify default behavior in the SaaS kit
- Team invitation policies with pre-checks using the Feature Policy API: Invite Members dialog now shows loading, errors, and clear reasons when invitations are blocked
- Version bump to 2.16.0 and widespread dependency updates (Supabase, React types, react-i18next, etc.).
- Added comprehensive docs for the new policy system and orchestrators.
- Subscription cancellations now trigger immediate invoicing explicitly

packages/policies/package.json

@@ -0,0 +1,29 @@
+{
+  "name": "@kit/policies",
+  "private": true,
+  "version": "0.1.0",
+  "exports": {
+    ".": "./index.ts"
+  },
+  "typesVersions": {
+    "*": {
+      "*": [
+        "src/*"
+      ]
+    }
+  },
+  "scripts": {
+    "clean": "rm -rf .turbo node_modules",
+    "lint": "eslint .",
+    "format": "prettier --check \"**/*.{mjs,ts,md,json}\"",
+    "typecheck": "tsc --noEmit"
+  },
+  "devDependencies": {
+    "@kit/eslint-config": "workspace:*",
+    "@kit/prettier-config": "workspace:*",
+    "@kit/shared": "workspace:*",
+    "@kit/tsconfig": "workspace:*",
+    "zod": "^3.25.74"
+  },
+  "prettier": "@kit/prettier-config"
+}