Add editorAutoFocusFileId state to automatically focus the editor when
a new text file is created. Improve tree-tab synchronization by adding
syncSignal/isTreeLoading guards, deduplicating rAF calls, and skipping
redundant select/openParents operations when the node is already active.
Switch from whitelist to blacklist pattern for determining editable files.
Files are now editable unless they are known binary types (audio, archives,
executables, Office documents, fonts, etc.), enabling support for any
runtime-generated text files without needing to add extensions one by one.