docs: add context-menu and preferences screenshots to README

Two static screenshots: the right-click Convert with Docling menu (lead
visual) and the preferences pane. Local scratch/ is gitignored.

Author: max3925vats

.gitignore

@@ -30,3 +30,6 @@ docs/PLAN.md
 
 # Note: typings/i10n.d.ts and prefs.d.ts ARE committed even though they are
 # scaffold-generated, so a fresh clone can typecheck before the first build.
+
+# Local scratch space (screenshots, disposable intermediates)
+scratch/

README.md

@@ -18,6 +18,8 @@ Markdown is plain text, so converted papers drop straight into note apps like
 Obsidian, AI/RAG pipelines, citation extraction, summarisation, literature
 reviews — anything that prefers text over PDFs.
 
+![Right-click a PDF attachment and choose "Convert with Docling"](docs/images/context-menu.png)
+
 ---
 
 ## Quick start
@@ -226,6 +228,8 @@ sections — **Conversion options** and **Advanced** — collapsed by default so
 the first-run experience stays focused on Server, Behavior, and Output.
 Click either header to expand. Hover any field for inline help.
 
+![The zotero-docling preferences pane: server URL with Test Connection, plus Behavior, Output, and Conversion options](docs/images/preferences.png)
+
 ### Exporting markdown to a .zip
 
 Once a set of items has been converted, you can bundle the markdown into a