feat(kb): split-view PDF jump-to-page for both ask and search modes

Search and ask modes now render results as a two-column layout: a left
column with ranked hit cards (search) or Shira's answer + source picker
(ask), and a right column with an iframe showing the source PDF scrolled
to page_number. Clicking a hit (search) or source pill (ask) swaps the
iframe's src, so users can verify a quote against the original PDF
without leaving the KB tab.

- search: renderSearchResults lays out results as panel cards on the
  left (with kind + title + section + "עמ׳ N" label); the top hit is
  pre-selected and its PDF loads on the right. Clicking any card
  re-highlights it and swaps the preview. Law-kind hits (Wikisource
  text) gracefully fall back to a chunk-text panel with a Wikisource
  link so the right pane never 404s on a text source.
- ask: renderAskAnswer dedups /kb/ask's sources[] by source_id,
  collects all cited pages per source, and renders a picker row plus
  per-source page-jump buttons. First source's first page loads on
  initial render; buttons swap the iframe without re-running the query.

Depends on shira-hermes commits e534709 + 1ca1cc0 (chunker page_number
propagation + null-byte strip) — without them, every PDF collapses to
page 1 in the DB and the jump links are cosmetic.

Refs Task Master #1

manifest.json

@@ -1,7 +1,7 @@
 {
     "name": "KnowledgeBase",
     "module": "KnowledgeBase",
-    "version": "0.1.7",
+    "version": "0.1.8",
     "acceptableVersions": [
         ">=8.0.0"
     ],