Search and large-vault polish — v0.1.0-beta.3

Beta 3 focuses on local search, document handling, and smoother browsing in larger encrypted vaults.

Global search now reaches deeper across notebooks, pages, Today captures, collections, threads, Cabinet media, and extracted document text.
Document search can index PDF, DOCX, Markdown, plain-text, and OCR-readable PDF content when document indexing is enabled.
Notebook search can find text inside documents embedded on a page and open the matching document from that page.

Cabinet browsing scales better for larger local vaults with paged media loading, bounded gallery views, and less eager preview work.
Document previews now load on demand for heavier files, reducing stalls around large PDFs and document-heavy pages.
PDF previews keep navigation steadier with previous-page retention, direct page entry, adjacent-page caching, and clearer search target placement.
Search result handoffs are more precise across page text, extracted document text, and Cabinet document detail views.
Editor media cards, gallery views, document detail panels, captions, usage links, and PDF controls have been polished.

Search highlights are preserved more reliably when opening results, including repeated terms and extracted document matches.
Stale, failed, unsupported, and missing document index states are surfaced instead of silently disappearing from search.
Media captions and embedded media remain more stable while galleries load or metadata changes.
Cabinet and media detail views avoid unnecessary full-vault loading in performance-sensitive flows.

Before installing a beta update, create and verify an encrypted .onbk backup from Settings.