Add title pages, standard manuscript format and collapsible panels

Five changes to the export and the window chrome:

* Manuscript details gains a contact field and a "Begin exports with a
  title page" option: the title, the author beneath it, and the contact
  details beneath that, laid out line for line as typed. A chapters +
  master export puts the title page on the master, not on each chapter.

* "Standard manuscript format" lays an export out the way an agent or an
  editor expects a submission: 12pt Courier, double-spaced, half-inch
  first-line indents, a Surname / Title / page header on every page but
  the title page, chapters opening a third of the way down, and `---`
  rendered as the conventional centred `#` scene break. The title page
  becomes the submission kind, with contact top-left and an approximate
  word count top-right. Off by default; margins were already the
  standard 1in on US Letter and are unchanged either way.

* A folder button beside Export ODT opens the project folder in the file
  manager -- the enclosing git work tree, including one still awaiting
  confirmation, since showing a folder is a smaller question than
  choosing which repository to commit to.

* The toolbar and the file list each collapse, from the pair of buttons
  at the right of the menu bar or from the View menu, and Ctrl+D folds
  both away together for distraction-free writing. Both choices persist.

* The editor sizes to its viewport instead of a fixed 30 rows, so the
  height a folded panel gives back reaches the page rather than leaving
  grey space below the text box that did not even take focus.

Two traps worth recording. ODF's style:master-page-name is inherited,
and any paragraph style carrying one forces a page break before every
paragraph that uses it -- a four-line contact block came out as four
pages until Contact_20_Line stopped inheriting from Contact_20_Block;
a test now pins which styles may carry one. And the status bar shares
a function with the toolbar, so guarding that function's top rather
than the top panel alone silently took the word counts away with it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GYSGPDwkSzhm4qLqjCbqxU

src/app/file_list.rs

@@ -105,7 +105,12 @@ pub(super) fn build_rows(files: &[String], collapsed: &HashSet<String>) -> Vec<R
 }
 
 impl App {
+    /// The file list down the left-hand side.
+    ///
+    /// Collapses through `show_animated`, which gives the width back to the
+    /// editor rather than leaving an empty column.
     pub(super) fn left_pane(&mut self, ctx: &egui::Context) {
+        let show_files = self.config.show_file_panel;
         egui::SidePanel::left("files")
             .resizable(true)
             .default_width(260.0)
@@ -113,7 +118,7 @@ impl App {
             // that asks for more width than there is would otherwise push it
             // wider every frame.
             .width_range(160.0..=460.0)
-            .show(ctx, |ui| {
+            .show_animated(ctx, show_files, |ui| {
                 // The default theme renders unselected list rows fairly dim; bump
                 // the widget text colours so file names stay legible (especially in
                 // dark mode) without affecting the rest of the app.