docs: regenerate JSON schemas from the API (#377)

Automated regeneration of the static JSON Schema files from the Kosli
API (source of truth in `kosli-dev/server`).

- `schemas/flow-template/v1.json` ← `GET
/api/v2/schemas/flow-template/v1`
- `schemas/policy/v1.json` ← `GET /api/v2/schemas/environment-policy/v1`

This PR only appears when the committed files have drifted from the API.

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

schemas/policy/v1.json

@@ -69,7 +69,7 @@
       "type": "object"
     },
     "PolicyExpression": {
-      "description": "Boolean expression evaluated against flow/artifact context. In YAML this is often written as a string wrapped in ${{ ... }}.",
+      "description": "Boolean expression evaluated against flow/artifact context. In YAML this is often written as a string wrapped in ${{ ... }}. A missing (None) context value never matches: matches() and the ordering comparisons (<, >, <=, >=) return false if either operand is missing, and `in` is a list-membership test that returns false unless its right-hand side is a list containing the left-hand value.",
       "properties": {
         "text": {
           "title": "Text",