feat(editeur): #93 edition inline — Editer/Forge remplacent la vue lecture

Le conteneur d'edition (#editor-container, CodeMirror ou iframe Forge) est deplace dans la zone de contenu du document (#content-area ou pane active) au lieu de l'overlay plein ecran : le mode edition remplace la vue lecture. L'overlay reste monte (transparent, pointer-events: none) car le ruban d'edition mobile y est ancre ; il ne sert plus que de repli quand la cible n'est pas le document affiche. Garde-fou dans renderFile() pour liberer proprement la session (destroy CodeMirror/Yjs, retrait de l'iframe Forge) ; forge-close passe par closeEditor() ; cache d'onglet invalide au retour en lecture.

Assistant IA : app_context.editing annonce le document en cours d'edition (frontend bookslm.js + backend bookslm.py), et chaque ecriture d'outil (edit_file, append_to_file, create_file, restore_backup) recharge le document affiche (obsigate:file-written) — tampon CodeMirror remplace avec auto-save neutralisee, parent-reload pour l'iframe Forge, re-rendu de la vue lecture sinon.

Tests : tests/frontend/editor-inline.test.mjs (19), tests/test_bookslm.py::TestGeneralPrompt (3 nouveaux). Fiche : docs/features/editeur-inline.md.

frontend/style.css

@@ -2795,6 +2795,47 @@ select {
   overflow: hidden;
   box-shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
 }
+
+/* --- Inline edition (#93) --------------------------------------------------
+   When a document is being edited, `#editor-container` is moved into the
+   document content area: the editor *replaces* the read view instead of
+   covering it with the overlay, so the AI assistant sidebar stays usable.
+   The overlay itself is neutralised but kept mounted (and `active`) because
+   the mobile editing ribbon (`#me-toolbar`, `.me-ribbon`) is anchored to it. */
+.editor-modal.editor-inline-mode {
+  display: block;
+  background: transparent;
+  padding: 0;
+  pointer-events: none;
+}
+.editor-modal.editor-inline-mode .me-ribbon {
+  pointer-events: auto;
+}
+.content-area.editor-inline-host,
+.pane-content.editor-inline-host {
+  display: flex;
+  flex-direction: column;
+  padding: 0;
+  overflow: hidden;
+}
+.content-area.editor-inline-host .editor-container.editor-inline,
+.pane-content.editor-inline-host .editor-container.editor-inline {
+  flex: 1;
+  height: auto;
+  width: 100%;
+  min-height: 0;
+  max-width: none;
+  max-height: none;
+  border: none;
+  border-radius: 0;
+  box-shadow: none;
+  background: var(--bg-primary);
+}
+.editor-container.editor-inline .editor-body,
+.editor-container.editor-inline .editor-body-cm {
+  flex: 1;
+  min-height: 0;
+}
 .editor-header {
   display: flex;
   align-items: center;