docs(site): [SITE-04] document Iframe and Thumbnail tools

refactor/changes/2026-09-16-SITE-04-tools-guides.md

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+# SITE-04 checkpoint: Iframe and Thumbnail tools
+
+Four bilingual guides describe the standalone tools separately from plugins.
+Navigation now has a tools section, retains the Iframe label and adds Thumbnail.
+Original JavaScript examples are copied unchanged; Iframe also explains the child
+page and required inject call. Generated route provenance records pre-change HEAD
+3aad294aa5eee5276afbd8b80330efb45a68d677.
+
+Iframe covers every public instance/static method and field, serialized commit,
+literal resolve behavior, callbacks, IDs, cancellation, document navigation,
+trusted peers and12 public types. It does not claim the historical package/helper
+is an alias, a type view validates data, or window checks constitute an origin
+allowlist. Thumbnail covers nine options, all methods/fields, eight events,
+10 types, density and midpoint geometry, PNG footer/download, approved defaults,
+synchronous versus Promise failures, emitter behavior and URL/resource ownership.
+The [content tracker](../site-content-review.md) maps sources and preserved limits.
+
+A stale paragraph in the thumbnail package's ARCHITECTURE.md still called
+aspect-derived height/synchronous video the default. It now correctly limits
+those behaviors to explicit workspace-4.4; published fixed height and delay remain
+the default. Runtime code and declarations did not change. This packaged document
+change correctly invalidates the old5.0.0 build envelope:20 other library builds
+remain accepted, while REL-02 must prepare a fresh thumbnail candidate next.
+
+## Verification
+
+- Node24.21.0, Yarn1.22.22, TypeScript5.9.3. Four exact TS snippets pass strict
+  NodeNext, skipLibCheck:false and types:[], including Iframe's resolver view and
+  Thumbnail event inference. Each new page validates40 local file/fragment targets.
+- All12 guide cases pass on Chromium153.0.8010.12, Firefox155.0 and Windows
+  WebKit26.6 with no retries/page errors: HTTP load, sidebar, visible Run Code,
+  original code/library forwarding and language switching. Popups are isolated,
+  so this is neither full editor/cross-window player execution nor file extraction.
+  Full-page screenshots retained; Chromium Chinese Thumbnail inspected.
+- Existing documentation/loading tests:17 pass,0 failures/skips,1195.3457ms.
+  Config lint, source/HTML inventories, demo paths, LLM generation/check and final
+  docs build pass. VitePress8.80s, Yarn10.36s. An initial build rejected unquoted
+  Promise<void> in Markdown as an HTML tag; inline-code formatting fixes both
+  languages. That failed log is retained separately from final evidence.
+- Current inventory:62 Markdown (31 per language),71 HTML,30 examples,
+  963 enumerated core members and204 assets. No new dependency/project script.
+
+See [the validation record](../baselines/site04-tools-guides.json). All16 plugins
+and both tools now have bilingual guides; both proxies, earlier-guide current
+checks and core semantic mapping remain. SITE-04 stays doing, totals224/22/39.
+User-directed formal reviews, actual device/SDK/media acceptance and publication
+are separate. No push, deployment or publication occurred.
+
+Revert this checkpoint to restore prior site navigation/generated assets and the
+old package documentation; keep the approved runtime default decision intact.
+
+Full staged whitespace checking exits2 for eight whitespace-only template lines
+in the four new generated HTML pages. Exact paths/lines and blank content were
+inspected; excluding only those pages passes. Generated output is preserved;
+the complete check is not reported as passing. See the evidence record.