Type-Safety Pass — Eliminated All `any` Declarations, Retired Hand-Rolled YAML Parser, Gated ESLint Into Build

Five-commit refactor that brings the project from 14 explicit `any` declarations to zero, replaces a structurally broken regex-based YAML parser with Obsidian's native frontmatter APIs (metadataCache.getFileCache + fileManager.processFrontMatter), introduces a small set of boundary coercers for narrowing untrusted values, and wires an ESLint flat-config mirroring ObsidianReviewBot's rules into `pnpm build` so the rules that gate community-store submission now fire locally pre-push. Verified working in a live Obsidian vault.