docs: add AI-OS maturity model

Author: OgeonX-Ai

docs/methodology/maturity-model.md

@@ -0,0 +1,25 @@
+# AI-OS Maturity Model
+
+Use this model to evaluate how mature an AI-assisted engineering workflow is.
+
+```mermaid
+flowchart TD
+    A[Level 0 Ad hoc] --> B[Level 1 Prompt templates]
+    B --> C[Level 2 Task loops]
+    C --> D[Level 3 Verifiers]
+    D --> E[Level 4 Governance]
+    E --> F[Level 5 Self improvement]
+```
+
+## Levels
+
+- Level 0: ad hoc chat.
+- Level 1: reusable prompts exist.
+- Level 2: task-specific loops exist.
+- Level 3: verifiers decide completion.
+- Level 4: CI, governance, release, and security controls exist.
+- Level 5: the system improves itself through a planned and reviewed loop.
+
+## Target
+
+This repository targets Level 5 for documentation and methodology, then moves toward executable local tooling.