Add Policy DSL Validator, Schema Exporter, and Simulation Smoke tools

- Implemented PolicyDslValidator with command-line options for strict mode and JSON output.
- Created PolicySchemaExporter to generate JSON schemas for policy-related models.
- Developed PolicySimulationSmoke tool to validate policy simulations against expected outcomes.
- Added project files and necessary dependencies for each tool.
- Ensured proper error handling and usage instructions across tools.

docs/examples/policies/internal-only.stella

@@ -0,0 +1,39 @@
+policy "Internal Only Policy" syntax "stella-dsl@1" {
+  metadata {
+    description = "Lenient policy for internal / dev tenants."
+    tags = ["internal","dev"]
+  }
+
+  profile severity {
+    env exposure_adjustments {
+      if env.exposure == "internal" then -0.4
+      if env.stage == "dev" then -0.6
+    }
+  }
+
+  rule block_kev priority 1 {
+    when advisory.has_tag("kev")
+    then status := "blocked"
+    because "Known exploited vulnerabilities must be remediated."
+  }
+
+  rule allow_medium_with_warning {
+    when severity.normalized == "Medium"
+         and env.exposure == "internal"
+    then warn message "Medium severity permitted in internal environments."
+    because "Allow Medium findings with warning for internal workloads."
+  }
+
+  rule accept_vendor_vex {
+    when vex.any(status in ["not_affected","fixed"])
+    then status := vex.status
+         annotate justification := vex.latest().justification
+    because "Trust vendor VEX statements for internal scope."
+  }
+
+  rule quiet_low_priority {
+    when severity.normalized <= "Low"
+    then ignore until "2026-01-01T00:00:00Z"
+    because "Quiet low severity until next annual remediation sweep."
+  }
+}