Introduces NoteContextBuilder to extract explicit wikilink mentions,
detect scope intent, and gather contextual note data including
backlinks, outlinks, and related notes. Integrates into ChatView
and adds comprehensive unit tests.
Also includes minor type fixes: removes unnecessary `as` cast in
action-preview-builder, fixes non-null assertion in tool-executor,
and cleans up unused import in auto-organizer. Simplifies auto-tag
command callback by removing redundant async/await.
