feat: completude de l'editeur Excel - mise en forme, sortie, concurrence, cache, outils IA #156

L'editeur lisait les styles mais ne les ecrivait pas, exportait la feuille
entiere et laissait le dernier-ecrivain gagner entre processus.

- A8 : bouton Mise en forme (gras/italique/souligne, alignements, couleurs via
  selecteur natif, formats de nombre, fusion, volets figes, largeur/hauteur) et
  nouvelle route PUT .../xlsx/style (verrou, backup, swap atomique, garde de
  perte, If-Match) ; A9 : decision "pas de moteur de formule" annoncee dans
  l'UI ; A10 : undo/redo unifie, piles par fichier conservees au re-rendu
- A11 : export de la selection + Markdown/HTML/impression et recherche sur
  toutes les feuilles ; A12 : concurrence optimiste (If-Match -> 409 reparable,
  retry qui relit) ; A13 : cache des metadonnees par (chemin, mtime, taille)
- A14 : outils IA .xlsm/.csv + search_workbook, analyze_range,
  edit_xlsx_structure
- tests : test_xlsx_styles.py (17), test_spreadsheet_tools.py (34),
  TestOptimisticConcurrency/TestMetaCache, JSDOM xlsx-viewer 107/107

README.md

@@ -2,7 +2,7 @@
 
 **Ultra-light web gateway for your Obsidian vaults** — Access, browse, and search all your Obsidian notes from any device via a modern, responsive web interface.
 
-[![Version](https://img.shields.io/badge/Version-2.44.1-blue.svg)]()
+[![Version](https://img.shields.io/badge/Version-2.45.0-blue.svg)]()
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
 [![Docker](https://img.shields.io/badge/Docker-Ready-blue.svg)](https://www.docker.com/)
 [![Python](https://img.shields.io/badge/Python-3.11+-green.svg)](https://www.python.org/)
@@ -84,7 +84,7 @@ Step-by-step **user guides** live in [`docs/GUIDES/`](docs/GUIDES/):
 - **🖼️ Obsidian Images** : Full support for all Obsidian image syntaxes with intelligent resolution
 - **🎬 Audio & video** : Built-in HTML5 players (`.mp3 .wav .flac .mp4 .webm`…) with HTTP Range streaming (play, seek, fullscreen) and **persistent playback** (floating mini-player / mini video window, return to media or stop anytime, lock-screen controls via Media Session), falling back to download when the format is not playable in the browser
 - **🎨 Excalidraw Diagrams** : Native viewer/editor for `.excalidraw` and `.excalidraw.md` files (sandboxed iframe, autosave, dark/light theme, diagram text indexed for search)
-- **📊 Excel Spreadsheets** : `.xlsx` and `.xlsm` files open in a dedicated viewer — one table per sheet with tabs, A1 headers and inline cell editing (`PUT /api/file/{vault}/xlsx/save`, automatic backup, atomic write), plus download of the original file. The viewer renders fonts, colors, merged cells and frozen panes, offers keyboard navigation, a formula bar, sort/filter/find, CSV export, sheet & row/column structure editing and a workbook dashboard (named ranges, charts/pivot detection, per-sheet stats); `.csv` is edited in the same grid (RFC 4180) while `.xls` and `.ods` open read-only. Workbooks holding elements ObsiGate cannot preserve (cached values, slicers, form controls, signature…) show a **warning** and ask for confirmation before saving; a value starting with `=` or `@` is stored as text unless the `f(x)` toggle is enabled. The AI assistant can list sheets, dump a bounded table to its context, update cells and append rows
+- **📊 Excel Spreadsheets** : `.xlsx` and `.xlsm` files open in a dedicated viewer — one table per sheet with tabs, A1 headers and inline cell editing (`PUT /api/file/{vault}/xlsx/save`, automatic backup, atomic write), plus download of the original file. The viewer renders fonts, colors, merged cells and frozen panes, offers keyboard navigation and shortcuts (`Ctrl+S`, `Delete`, `F2`, `Ctrl+Home/End`, `PgUp/PgDn`, `Ctrl+arrows`), a formula bar with function suggestions, an editable Name Box ("go to" `A1:B3`), a range clipboard (copy/cut/paste a block, from or to Excel), a **Format** menu (bold/italic/underline, alignments, font & fill colours, number formats, merges, frozen panes, column width/row height — `PUT /api/file/{vault}/xlsx/style`), sort/filter/find across every sheet, CSV/Markdown/HTML export and printing (selection or sheet), sheet & row/column structure editing and a workbook dashboard (named ranges, charts/pivot detection, per-sheet stats); `.csv` is edited in the same grid (RFC 4180) while `.xls` and `.ods` open read-only. Workbooks holding elements ObsiGate cannot preserve (cached values, slicers, form controls, signature…) show a **warning** and ask for confirmation before saving; a value starting with `=` or `@` is stored as text unless the `f(x)` toggle is enabled, and concurrent writes from another process are detected (`If-Match` → "Retry"). The AI assistant can list sheets, dump a bounded table to its context, search the workbook, analyze a range, update cells and append rows — on `.xlsx`, `.xlsm` and `.csv`
 - **🎨 Syntax Highlight** : Syntax highlighting for code blocks
 - **🌓 Light/Dark Theme** : Toggle persisted in localStorage
 - **📡 Real-time Sync** : Automatic file monitoring via watchdog with incremental index updates
@@ -1151,8 +1151,8 @@ This project is licensed under the **MIT License** - see the [LICENSE](LICENSE)
 
 ## 📝 Changelog
 
-See [CHANGELOG.md](./CHANGELOG.md) for the complete version history (v1.0.0 → v2.44.1).
+See [CHANGELOG.md](./CHANGELOG.md) for the complete version history (v1.0.0 → v2.45.0).
 
 ---
 
-*Project: ObsiGate | Version: 2.44.1 | Last updated: September 2026*
+*Project: ObsiGate | Version: 2.45.0 | Last updated: September 2026*