Modular refactor + dev section

Restructured the site from a single 380-line index.html into a small modular src/ tree that builds back into one fully-inlined, contract-clean index.html. Behaviour and visuals are unchanged; the codebase is now testable and easy to extend.

• Three-tier architecture under src/: pure core/ logic (risk-queue state machine, a safe Markdown parser, version formatting), a thin services/ IO edge for reading vault files, and components/ as light-DOM custom elements (rm-risk-queue, rm-dev-releases).
• Build-inline pipeline (build.js): authoring stays modular, but the shipped artifact is a single inlined file so it runs identically in the SG/App host, the vault preview, and the static domain.
• Unit tests with node:assert cover the pure core with known-answer vectors; the build runs them as a gate alongside syntax, contract, and version-lockstep checks.
• New Dev section (this one) renders these release notes live from dev/releases/.
• New versioning: the version now lives in a bare version file; release details live as Markdown in dev/releases/, replacing version.json, CHANGELOG.md, and the standalone changelog page.