Fix component bugs across hooks, elements, form, layout, editors and utils

- Hooks: per-instance timers in useReady; cleanup for useIntersectionObserver;
  useWebSocket no longer reconnects after unmount/refresh, drains the queue
  and dispatches non-JSON messages
- Modal/Popover/Dropdown: onClose only on close, Escape to close, no stray
  DOM props, hooks before early return, scrollbar-aware positioning,
  top-left/top-right dropdown positions
- Elements: Toast/Search/StarRating per-instance timers, Pagination labels
  and empty state, Breadcrumbs titles, LinkList dividers/props, segment-wise
  active-link matching (new utils/link-matches-path), Table object cells
- Form: Select with a default option is changeable, Input clear notifies
  controlled parents and copy works on textareas, Checkbox random label,
  NumberInputButtons runaway interval, upload prop/spread fixes
- Layout: Button disabled while loading, Stack gap and Span truncate via
  inline styles, Img fallbackImageSrc, className/JSDoc fixes
- Editors/MDX/AI: TinyMCE id/cleanup/stale handler/duplicate scripts,
  AceEditor debounce, markdown heights and frontmatter regex, last
  assistant message, AIPromptBlock prompt ref
- Utils: fetchApi headers/FormData/fetchOptions/no mutation, base64 file
  names and read errors, slugify underscore trim, serializeQuery zero values
- Tests for fetchApi, link matching, slugify and serializeQuery
- AGENTS.md updated for the package layout

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/utils/serialize-query.test.ts

@@ -57,4 +57,9 @@ describe("twuiSerializeQuery", () => {
         const result = twuiSerializeQuery({ active: true as any });
         expect(result).toContain("active=true");
     });
+
+    test("keeps zero values", () => {
+        const result = twuiSerializeQuery({ page: 0, foo: "bar" });
+        expect(result).toContain("page=0");
+    });
 });