feat: scaffold deployment-policies monorepo

OPA/Rego deployment gateway policies: 5 rules (valid-environment,
require-approvals, no-self-approval, block-weekends, freeze-window),
a deploy-gate combining them, JSON schemas, scenario-driven tests,
Gitea Actions CI (verify + publish to generic registry), changesets
versioning, Makefile and scripts.

policies/rules/no-self-approval/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "no-self-approval",
+  "version": "0.0.0",
+  "description": "Denies deployments where the requestor approved their own deployment.",
+  "private": true
+}

policies/rules/no-self-approval/policy.rego

@@ -0,0 +1,25 @@
+# METADATA
+# schemas:
+#   - input: schema["input"]
+#   - data: schema["data"]
+
+package rules.no_self_approval
+
+import rego.v1
+
+default allow := false
+
+allow if {
+	count(violations) == 0
+}
+
+violations contains {"code": "self_approval", "message": sprintf("approval by %q is the deployment requestor", [input.deployment.requested_by])} if {
+	some approval in input.approvals
+	approval.active
+	approval.by == input.deployment.requested_by
+}
+
+violations contains {"code": "missing_requestor", "message": "deployment has no requestor"} if {
+	input.deployment
+	not input.deployment.requested_by
+}

policies/rules/no-self-approval/policy_test.rego

@@ -0,0 +1,12 @@
+package rules.no_self_approval_test
+
+import data.rules.no_self_approval as rule
+import rego.v1
+
+test_scenarios[scenario_name] if {
+	some scenario_name, scenario in data.scenarios
+	actual := {code | code := rule.violations[_].code} with input as scenario.input with data.deploygate as scenario.data
+	expected := {code | code := scenario.expect.violations[_]}
+	actual == expected
+	rule.allow == scenario.expect.allow with input as scenario.input with data.deploygate as scenario.data
+}

policies/rules/no-self-approval/scenarios.json

@@ -0,0 +1,76 @@
+{
+  "scenarios": {
+    "others_approve": {
+      "input": {
+        "deployment": {
+          "environment": "production",
+          "service": "payments-api",
+          "version": "1.2.3",
+          "requested_by": "alice",
+          "created_at": "2026-09-15T10:00:00Z"
+        },
+        "approvals": [
+          {"by": "bob", "at": "2026-09-15T09:00:00Z", "active": true},
+          {"by": "carol", "at": "2026-09-15T09:30:00Z", "active": true}
+        ]
+      },
+      "data": {
+        "config": {
+          "production": {"min_approvals": 2}
+        }
+      },
+      "expect": {
+        "allow": true,
+        "violations": []
+      }
+    },
+    "self_approval": {
+      "input": {
+        "deployment": {
+          "environment": "production",
+          "service": "payments-api",
+          "version": "1.2.3",
+          "requested_by": "alice",
+          "created_at": "2026-09-15T10:00:00Z"
+        },
+        "approvals": [
+          {"by": "alice", "at": "2026-09-15T09:00:00Z", "active": true},
+          {"by": "bob", "at": "2026-09-15T09:30:00Z", "active": true}
+        ]
+      },
+      "data": {
+        "config": {
+          "production": {"min_approvals": 2}
+        }
+      },
+      "expect": {
+        "allow": false,
+        "violations": ["self_approval"]
+      }
+    },
+    "revoked_self_approval_ignored": {
+      "input": {
+        "deployment": {
+          "environment": "production",
+          "service": "payments-api",
+          "version": "1.2.3",
+          "requested_by": "alice",
+          "created_at": "2026-09-15T10:00:00Z"
+        },
+        "approvals": [
+          {"by": "alice", "at": "2026-09-15T09:00:00Z", "active": false},
+          {"by": "bob", "at": "2026-09-15T09:30:00Z", "active": true}
+        ]
+      },
+      "data": {
+        "config": {
+          "production": {"min_approvals": 2}
+        }
+      },
+      "expect": {
+        "allow": true,
+        "violations": []
+      }
+    }
+  }
+}

policies/rules/no-self-approval/schema/data.json

@@ -0,0 +1,15 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "type": "object",
+  "additionalProperties": true,
+  "properties": {
+    "deploygate": {
+      "type": "object",
+      "additionalProperties": true
+    },
+    "rules": {
+      "type": "object",
+      "additionalProperties": true
+    }
+  }
+}

policies/rules/no-self-approval/schema/input.json

@@ -0,0 +1,27 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "type": "object",
+  "additionalProperties": true,
+  "properties": {
+    "deployment": {
+      "type": "object",
+      "additionalProperties": true,
+      "required": ["requested_by"],
+      "properties": {
+        "requested_by": {"type": "string"}
+      }
+    },
+    "approvals": {
+      "type": "array",
+      "items": {
+        "type": "object",
+        "additionalProperties": true,
+        "required": ["active", "by"],
+        "properties": {
+          "active": {"type": "boolean"},
+          "by": {"type": "string"}
+        }
+      }
+    }
+  }
+}