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

.env.example

@@ -0,0 +1,12 @@
+# API Keys (Required to enable respective provider)
+ANTHROPIC_API_KEY="your_anthropic_api_key_here"       # Required: Format: sk-ant-api03-...
+PERPLEXITY_API_KEY="your_perplexity_api_key_here"     # Optional: Format: pplx-...
+OPENAI_API_KEY="your_openai_api_key_here"             # Optional, for OpenAI models. Format: sk-proj-...
+GOOGLE_API_KEY="your_google_api_key_here"             # Optional, for Google Gemini models.
+MISTRAL_API_KEY="your_mistral_key_here"               # Optional, for Mistral AI models.
+XAI_API_KEY="YOUR_XAI_KEY_HERE"                       # Optional, for xAI AI models.
+GROQ_API_KEY="YOUR_GROQ_KEY_HERE"                     # Optional, for Groq models.
+OPENROUTER_API_KEY="YOUR_OPENROUTER_KEY_HERE"         # Optional, for OpenRouter models.
+AZURE_OPENAI_API_KEY="your_azure_key_here"            # Optional, for Azure OpenAI models (requires endpoint in .taskmaster/config.json).
+OLLAMA_API_KEY="your_ollama_api_key_here"             # Optional: For remote Ollama servers that require authentication.
+GITHUB_API_KEY="your_github_api_key_here"             # Optional: For GitHub import/export features. Format: ghp_... or github_pat_...