docs: add MIT license, security policy, and README legal section

Include SECURITY.md for private vulnerability reporting; fix CONTRIBUTING upstream URL.

Co-authored-by: Cursor <cursoragent@cursor.com>

CONTRIBUTING.md

@@ -13,7 +13,7 @@
 2. 克隆你的 Fork，并添加上游（便于同步）：
 
    ```text
-   git remote add upstream https://github.com/<原仓库>/oclaw.git
+   git remote add upstream https://github.com/hansjone/oclaw.git
    ```
 
 3. 从 `main` 拉最新，并创建功能分支（命名清晰，如 `fix/...`、`feat/...`）：

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 hansjone and contributors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -153,3 +153,8 @@ Chinese zero-to-running checklist: see **开箱即用（从零跑起来）** at
 
 See `docs/ENVIRONMENT_VARIABLES.md` for full runtime variable reference.
 
+## License and security
+
+- License: [MIT](LICENSE). Third-party subtrees may carry their own license files; those terms apply to the respective files only.
+- Vulnerability reporting: [SECURITY.md](SECURITY.md).
+

SECURITY.md

@@ -0,0 +1,21 @@
+# Security policy
+
+## Supported versions
+
+Security fixes are applied on the default branch (`main`) when practical. Use the latest commit for deployments.
+
+## Reporting a vulnerability
+
+Please **do not** open a public GitHub issue for undisclosed security problems.
+
+Use **GitHub private vulnerability reporting** for this repository:
+
+[Submit a private security advisory](https://github.com/hansjone/oclaw/security/advisories/new)
+
+Include:
+
+- A short description of the impact
+- Steps to reproduce (or proof-of-concept) if you can share them safely
+- Affected component or path (if known)
+
+We will treat reports as confidential and coordinate a fix and disclosure timeline with you when possible.