docs(ui): commit the #237/#238 interactive mockups into the repo

docs/mockups/README.md

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+# UI mockups
+
+Interactive, self-contained HTML mockups for screens that are not built yet.
+Open them directly in a browser (double-click; no server, no network, no
+account — fonts and data are embedded). Each one is loaded with **real data
+from this repo**, so counts and behaviors are what the real screen will show.
+
+| Mockup | Issue | Data |
+|---|---|---|
+| [`search-parameter-editor.html`](search-parameter-editor.html) | [#238](https://github.com/HeliosSoftware/hfs/issues/238) | `data/search-parameters-r4.json` (1,375 params, 135 base types) |
+| [`compartment-editor.html`](compartment-editor.html) | [#237](https://github.com/HeliosSoftware/hfs/issues/237) | `crates/fhir-gen/resources/R4/compartmentdefinition-*.json` |
+
+A static `.png` preview sits next to each file.
+
+## Relationship to the real screens
+
+These are **prototypes, not the implementation**. Per the `helios-ui` crate
+rules, the real markup lives in `templates/` (Askama), interactions are htmx
+fragment swaps served by the server, and read paths work with JavaScript
+disabled. The mockups' inline JS stands in for what will be server round
+trips — e.g. the compartment route tester becomes a `GET /ui/compartments/test`
+fragment, and the SearchParameter table reads the live registry (storage-backed
+after #235) instead of an embedded snapshot.
+
+Style is the crate's design system verbatim: `crates/ui/assets/app.css` tokens,
+the vendored Figtree face (inlined as a data URI), and both themes via
+`prefers-color-scheme` plus the `data-theme` override — with `--ok` / `--warn` /
+`--danger` added as semantic tokens held off the accent hue.
+
+The SearchParameter editor's validation reflects the registry semantics after
+#242: a cross-source `(base, code)` shadow is a supported override (chip:
+`overrides spec`), a same-source collision is a blocking `conflict`
+(`RegistryError::DuplicateCode`).