chore(repo): Align web app linting and policy docs

Tighten the web app ESLint scope so TypeScript source is checked
without crawling bundled skill assets, and remove unused markdown and
debounce dependencies.

Clarify the security reporting flow and split code vs content
licensing to reduce ambiguity for users and contributors.

LICENSE-CONTENT

@@ -0,0 +1,15 @@
+Creative Commons Attribution 4.0 International (CC BY 4.0)
+
+This file clarifies the license for original non-code repository content.
+
+- Original code and tooling remain licensed under the MIT License in `LICENSE`.
+- Original documentation and other non-code written content are licensed under
+  the Creative Commons Attribution 4.0 International license unless a more
+  specific upstream notice says otherwise.
+- Third-party attributions, upstream licenses, and exceptions are tracked in
+  `docs/sources/sources.md`.
+
+Canonical license URL:
+https://creativecommons.org/licenses/by/4.0/
+
+Review the full license text at the canonical URL before reuse.