feat(posts): add EP73 Axiom logging episode with cover art and transcript support

AGENTS.md

@@ -2,7 +2,7 @@
 
 ## Project Structure & Module Organization
 
-AsyncTalk is an Astro content site for a Chinese web development podcast. Source code lives in `src/`: pages in `src/pages`, layouts in `src/layouts`, shared UI in `src/components`, global styles in `src/global.css`, and content configuration in `src/content.config.ts`. Podcast episodes are MDX files in `src/content/posts` using names such as `ep59.mdx`. Episode media belongs under `src/assets/<episode>/` when imported by Astro; public static files live in `public/`.
+AsyncTalk is an Astro content site for a Chinese web development podcast. Source code lives in `src/`: pages in `src/pages`, layouts in `src/layouts`, shared UI in `src/components`, global styles in `src/global.css`, and content configuration in `src/content.config.ts`. Podcast episodes are MDX files in `src/content/posts` using names such as `ep59.mdx`. Episode media belongs under `src/assets/<episode>/` when imported by Astro; public static files live in `public/`. Two pieces of episode media are resolved by path convention rather than frontmatter, so they appear as soon as the file lands and are skipped while it is missing: square cover art at `src/assets/<episode>/cover.{jpg,jpeg,png,webp}` and subtitles at `public/subtitles/<episode>.srt`.
 
 ## Build, Test, and Development Commands
 

CLAUDE.md

@@ -40,6 +40,7 @@ This is a content-driven static site using Astro's content collections system:
 
 - **No Testing Framework**: This project currently has no automated tests. When implementing features, manual testing is required.
 - **Content Management**: New episodes should be added as MDX files in `src/content/posts/` following the existing naming pattern (epX.mdx).
+- **Episode Media**: Cover art and subtitles are declared in frontmatter, both optional. `cover` is a path relative to the MDX file (e.g. `../../assets/ep73/cover.png`), resolved by the schema's `image()` helper; it renders beside the title at its natural aspect ratio and feeds JSON-LD `image` plus the RSS `<itunes:image>`. `srt` is a path under `public/` (e.g. `/subtitles/ep73.srt`), parsed at build time into an on-page 文字稿 section, a download link, and JSON-LD `transcript` — a declared file that is missing fails the build.
 - **Build Process**: Always run `pnpm astro check` before building to catch TypeScript errors in Astro components.
 - **Episode Metadata**: Ensure all required frontmatter fields are properly filled when creating new episodes to maintain RSS feed compatibility.
 - **Chinese Language**: All content and UI copy should be in Chinese. Pay attention to proper font rendering and character encoding.