Fork Notesium source and restructure into Go package layout

Initial fork of github.com/alonswartz/notesium into librenotes:
- Source moved to internal/notesium/ (package notesium)
- Thin entry point at cmd/librenotes/main.go
- Module renamed to git.librete.ch/public/librenotes
- main() exposed as notesium.Run()
- LICENSE preserved (MIT), NOTICE added with attribution
- Web assets and completion.bash co-located with embedding code
  to satisfy go:embed path constraints

Closes #3, #34, #35.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

internal/notesium/web/app/state.js

@@ -0,0 +1,29 @@
+const { reactive, watch } = Vue;
+
+const defaultState = {
+  showGraphPanel: false,
+  showLabelsPanel: false,
+  showNotesPanel: false,
+  showNoteSidebar: true,
+  notesPanelDarkMode: false,
+  notesPanelCompact: false,
+  notesPanelCompactLabels: true,
+  sidePanelSortNotes: 'title', // title, links, mtime, ctime
+  sidePanelSortLabels: 'title', // title, links
+  editorFoldGutter: false,
+  editorLineWrapping: false,
+  editorConcealFormatting: true,
+  editorVimMode: false,
+  startOfWeek: 1, // 0 for Sunday, 1 for Monday, ...
+};
+
+const savedState = localStorage.getItem('notesiumState');
+const initialState = savedState ? JSON.parse(savedState) : defaultState;
+const notesiumState = reactive({ ...defaultState, ...initialState });
+
+watch(notesiumState, (newState) => {
+  Object.assign(newState, { ...defaultState, ...newState });
+  localStorage.setItem('notesiumState', JSON.stringify(newState));
+}, { deep: true });
+
+export { notesiumState };