fix(docs): add missing quick links + LLM no-mention rule + fix fence tag

- DEV_DOCS.md: add contributing guide and code of conduct to Quick links
  (PR description claimed they were linked; they weren't)
- DEV_DOCS.md: change unsupported \`\`\`text fence to \`\`\` (VuePress 1)
- AGENTS.md: add LLM no-mention rule carried over from old CLAUDE.md
  ("do not mention AI tool names in commits, PRs, comments, docs")

Author: marcin-kordas-hoc

AGENTS.md

@@ -22,6 +22,7 @@ Prefer reading these local files over fetching the rendered documentation from t
 - Ask clarifying questions when the request is ambiguous rather than guessing.
 - If you do not know something, say so and ask for help.
 - When answering from project documentation, quote the exact relevant fragments to support your claim.
+- In commit messages, PR descriptions, code comments, and documentation: do not mention the names of AI tools used for code generation.
 
 ## Common ways agents fail
 

DEV_DOCS.md

@@ -6,14 +6,16 @@ Canonical reference for everyone working on the HyperFormula source code: mainta
 
 - **[Building, testing, and linting](docs/guide/building.md)** — all `npm` commands and build outputs
 - **[Test suite](test/README.md)** — smoke tests and how to attach the private test suite
+- **[Contributing guide](docs/guide/contributing.md)** — contributor flow, CLA, branch policy
+- **[Code of conduct](docs/guide/code-of-conduct.md)**
 - **[Public docs portal](https://hyperformula.handsontable.com/docs)** — main documentation
 - **[Docs README](docs/README.md)** — how to run the docs portal locally
 - **[Changelog](CHANGELOG.md)**
 - **[Pull request template](.github/pull_request_template.md)**
 
 ## Repository layout
 
-```text
+```
 .
 ├── src/                        # Source code
 │   ├── HyperFormula.ts         # Main engine class, public API entry point