docs(core): [SITE-04] document template and icon contracts

refactor/changes/2026-09-16-SITE-04-template-icons.md

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+# SITE-04 checkpoint: template and icon contracts
+
+The two advanced-properties guides now explain cached template nodes, the original
+container's query scope, proxy media/track references, optional mini-window nodes,
+SSR markup reuse, template initialization/cleanup and whole-player destruction.
+The two static-property guides clarify that Artplayer.html is a static base template.
+Historical root declarations retain the nonexistent template.html instance member;
+the guide directs consumers to the actual static entry without changing types.
+
+All 27 default icon names share fresh I wrappers, nonenumerable readonly getters,
+captured constructor options and HTMLElement movement rather than cloning. Root
+HTMLDivElement declarations remain compatible; runtime types describe HTMLElement
+and potentially missing custom keys. Trusted HTML and node ownership are explicit.
+No production source, public declaration, dependency or project script changed.
+
+The [mapping](../core-content-review.json) adds 62 template and 29 icon declaration
+records. Total: 172 reviewed, 791 remaining out of 963. These include root/runtime
+aliases and overloads, not independent feature counts. Each previous service group's
+source hashes were verified unchanged, and its relevant guide section compared
+with a1488f11b after LF normalization before refreshing the whole-document hash.
+Unrelated declaration groups are not implicitly accepted.
+
+## Verification
+
+- Four guides preserve all existing Run Code snippets. Four TS fences pass strict
+  NodeNext with skipLibCheck:false and types:[]. Local page links/fragments resolve.
+- Chromium 153.0.8010.12, Firefox 155.0 and Windows WebKit 26.6 pass 12 page cases
+  and 18 exact-code popup forwarding checks. Popup destinations are isolated;
+  this does not execute the editor. Two Chromium screenshots were inspected.
+- Each engine passes 63 real DOM assertions against core UMD bytes matched to the
+  registered candidate: all 23 node bindings, query identity/scope/errors, media
+  aliases, static HTML, all 27 icon getters, node movement, captured options,
+  retained destroy(false) markup, complete SSR reuse and default destruction.
+  No retry or page error. This is not media/codec/physical-device acceptance.
+- Existing template, DOM, entry, mini-window and documentation tests: 31 pass,
+  zero fail/skip, 1457.7521ms. The first run had 30 pass and one stale llms.txt
+  failure because generation had not run; both logs are retained. After generation
+  the same test selection passes. No assertion was removed or weakened.
+- Node 24.21.0 / Yarn 1.22.22 / TypeScript 5.9.3. Final docs build 9.28s
+  (Yarn 10.90s), LLM generation/check, site inventory and demo-route checks pass.
+  Inventory remains 66 Markdown, 75 HTML, 30 examples and 204 assets.
+- All 21 library build envelopes remain valid; release blockers are unchanged.
+
+See [evidence](../baselines/site04-template-icons.json). SITE-04 remains doing,
+224/22/39 unchanged. Continue remaining core groups; formal review rounds remain
+user-directed. No push, deployment or publication. Revert this checkpoint to
+restore the guides, generated pages and mapping changes together.