fix(catalog): tag discovery tutorial by interface (mcp, api); split out video section

[aaitor]

Why this matters

Two small presentation fixes to the "What's in the Catalog?" discovery tutorial (follow-up to #67), from review feedback:

1. It was tagged ts, implying a TypeScript-only tutorial. Discovery is language-agnostic — every surface (REST catalog, MCP tools, ARD registry, crawler feed) is a plain HTTP/MCP call from any language, shown as curl. It now carries two interface tags, mcp and api, so a Python or Go developer isn't wrongly filtered out.
2. The guided-tour video and the interactive demo now live in separate sections — §4 See it run is the working, live demo; §5 Catalog video is the walkthrough — so the two aren't conflated in one panel.

What changed

• lib/types.ts — add an agnostic Language plus a languageTags() helper that maps a language to its chip(s): agnostic → ["mcp","api"], everything else → its single existing label. One source of truth for all render sites.
• app/t/[slug]/page.tsx — render one chip per tag; add §5 "Catalog video" (discover tutorials only) and drop the video from the demo panel.
• app/page.tsx (gallery) & components/AppShell.tsx (sidebar) — render tags via the helper. This also fixes the sidebar, which rendered the raw language value (it would have shown agnostic).
• components/DiscoverPanel.tsx — no longer renders the video (moved to §5).

Additive: ts/py/autonomous tutorials render exactly as before.

Test plan

• node lib/demo-agent.mjs + node lib/catalog-discovery.mjs — self-checks pass.
• npm run build — green (type-checks LANGUAGE_LABEL totality and content/tutorials.ts); 17 static pages.
• Verified live in the local dev server: header shows two chips mcp api; sidebar shows mcp api (no raw agnostic); §4 is the live demo (8 result cards, facet bars fill) with no video; §5 "Catalog video" holds the player; other tutorials unchanged.

Follow-up to #67.

🤖 Generated with Claude Code

https://claude.ai/code/session_01NJVmLG9aiAzymDX4n56duk

[r-marques]

👀 Reviewing

[r-marques]

🤖 Automated PR review — 🟡 Mergeable with nits

Retags the catalog-discovery tutorial from ts to a new language-agnostic variant rendered as two interface chips (mcp, api), and lifts the guided-tour video out of DiscoverPanel into its own §5 on the tutorial page. The retag is substantively right and the refactor is clean — languageTags() is a single source of truth with a total fallback, so every render site moves together. Nits only; nothing blocks.

What I reviewed

• Diff range origin/main...HEAD — 6 files, +58/−23, head 3735f6b0.
• Panel: none — my own source-level verification of each claim.
• Checked the retag against the tutorial's own content, not the PR title: tutorials.ts tech.stack is ["REST catalog API", "Catalog MCP", "ARD registry", "/.well-known/ard.json", …] and a learn bullet reads "Query it as an agent over REST, the Catalog MCP (search_services), and the ARD registry". So ts was genuinely wrong — nothing in this tutorial is TypeScript-specific — and mcp + api describes it.
• Verified the new §5 can't leave a numbering gap: §1–§4 in app/t/[slug]/page.tsx (:73, :89, :126, :167) are all unconditional, and §5 is the only conditional one, so a discover tutorial reads 1-2-3-4-5 and every other tutorial reads 1-2-3-4.
• Confirmed the video move is behaviour-preserving: discoverVideo is gated on t.run.kind === "discover", which is exactly the set DiscoverPanel used to receive, and the <track> list plus the no-playback fallback text carried over verbatim.
• Checked for a language filter that would need the new variant added — there is none; Language appears outside lib/types.ts only as an AppShell prop type, so no filter UI goes stale.
• Checked the sidebar CSS for a width cap that two words could overflow: .sb-item .lang (globals.css:128) sets only margin-left:auto and a font — no fixed width, no truncation — so the longer value is cosmetic, not clipped.

Verdict: 🟡 Mergeable with nits — 0 blockers, 0 should-fix, 3 nits.

🧭 Inline comments (4)

Each is posted on its line in Files changed.

• 💡 NIT — A "mcp" language chip collides with the existing Protocol value of the same name — showcase/lib/types.ts:152
• 💡 NIT — Sidebar joins the tags with a bare space, so two tags read as one token — showcase/components/AppShell.tsx:111
• 💡 NIT — This label can never render — LANGUAGE_TAGS always shadows it for agnostic — showcase/lib/types.ts:145
• ✅ NICE — Narrowing on run.kind keeps the video move behaviour-preserving — showcase/app/t/[slug]/page.tsx:35

[r-marques]

🟡 Approved with comments — no blockers; 0 should-fix, 3 nit(s) left inline.

Inline review: #68 (review)