docs: the import rules the corpus turned up

src/lib/import/CLAUDE.md

@@ -24,6 +24,10 @@ The **Open .odt** button (`App.svelte`) parses an uploaded file with `importOdt(
 - **Content controls** (`inlineChildren`, DOCX): a `w:sdt` inside a paragraph — Word wraps every citation and bibliography entry in one — is walked through to its `w:sdtContent`, or the runs inside it never reach the paragraph (the thesis fixture lost every `[7]`-style reference and broke its lines one page short).
 - **Formulas** (`convertFormulaFrame`): a `<draw:frame>` whose `<draw:object>` resolves to a sub-document with a `math:math` root (or holds one inline) → a `formula` node. Our own `<annotation encoding="application/x-tex">` is preferred; LibreOffice strips it, so the MathML is parsed back to LaTeX instead. **`display` comes from the paragraph** (`aloneInParagraph`), not the object — LibreOffice writes `display="block"` on every formula it re-saves. DOCX: `m:oMath`/`m:oMathPara` sit beside the `w:r` runs in their own namespace, so `convertInline` probes them ahead of its `namespaceURI !== W` guard (that guard silently dropped every Word formula). See `docs/architecture/formulas.md`.
 - **Bookmarks & cross-references**: `text:bookmark-start`/`-end` (ODF) and `w:bookmarkStart`/`End` (DOCX) become a `bookmark` **mark** on the text they cover; the open ranges live in `Ctx` because Word writes them beside paragraphs as well as beside runs, and a range may close in a later paragraph. A **point** bookmark has no range to mark and is dropped, `_GoBack` with it. `text:bookmark-ref` and `REF`/`PAGEREF` fields (the `fldChar` machine and `w:fldSimple` alike, including a field Word left unresolved) become `crossRef` nodes carrying the producer's cached text. A `w:hyperlink w:anchor` with no `r:id` is an internal link → `#name`. See `docs/architecture/formatting.md`.
+- **Page geometry is the *body's* master page**, not the one named `Standard`: the importer counts the blocks each `style:master-page-name` governs and re-reads geometry (and the app's own header/footer) from the winner. A document whose Standard master no paragraph references would otherwise take margins — and a footer band — no page of it has. A **master switch always breaks the page** (LibreOffice's "page break with page style"), except for the master the document opens with; `fo:break-after="page"` becomes the next block's `breakBefore`, the only break the editor stores. A master with a `style:next-style-name` is itself the different-first-page flag: its own (possibly absent) zones govern page one.
+- **A page-anchored frame** (`text:anchor-type="page"`) is out of the flow: it rides a paragraph of its own that collapses to nothing, and the node view places it from its page's corner behind the text (`anchorPage`, `image.ts`). In a cell it falls back to an ordinary floating frame.
+- **A header/footer zone is fitted to its schema** (`fitZoneSchema`): the zone editor has fewer marks and nodes than the body, and one it doesn't know makes `generateHTML` throw — which renders the whole zone blank. Unknown marks are dropped, unknown nodes leave their text.
+- **A hoisted text box keeps what its anchor paragraph gave it**: an as-char figure frame is centred by the paragraph it sits in, so `wrapAlign` carries that (or the frame's own `style:horizontal-pos`) onto the box. Its `fo:padding` is read too — the editor's own 0.15cm ring is only the default.
 - **Graceful degradation** (collected as `warnings`, surfaced once): footnotes/comments dropped, hyperlinks flattened to text, nested tables flattened to paragraphs, non-`Pictures` drawings dropped, unreadable pictures skipped (each with a warning). Page size is normalized to A4. Floating/wrapped images are imported as left/right/top-bottom wrap (free x/y positions collapse to the nearest side; see `image.ts`).
 
 `tests/roundtrip.test.ts` (export→import) and `tests/lo-roundtrip.test.ts` (export→LibreOffice re-save→import, needs `soffice`) verify the round trip; run with `npm test` / `npm run test:lo`.