refactor: A28 TERMINÉ — board.py (2 101 L) → package 14 fichiers (v7.32.0)

Lot 4/4 de l'A28 (god files) : l'ancien app/routers/board.py (2 101
lignes, 53 routes) devient le package `app/routers/board/` :

- 12 modules de routes : pages 271 L (7 r.), page_api 229 (5),
  board_views 223 (8), page_ops 176 (3), sharing 175 (10), synced 144 (8),
  page_media 122 (4), import_ 85 (2), wiki 76 (2), library 66 (1),
  embed 64 (2), sync 51 (1)
- _common.py (878 L) : 23 helpers dont 4 async + les 4 constantes
  (STATUS_COLORS, STATUS_LABELS, AI_KEYWORD_COLORS, _REPO_REF_RE)
- __init__.py : __all__ complet — importateurs inchangés (api.py ×4
  top-level, webhooks top-level, dashboard ×5 lazy, tests ×4)

Preuve contractuelle : docs/openapi-v2.json régénéré = IDENTIQUE
byte-à-byte (509 chemins, ordre préservé).

Pièges rattrapés :
- constantes d'état oubliées dans _common à la 1ʳᵉ passe (F821 +
  ImportError au chargement) → ré-insérées avec les valeurs exactes
- docstring du header copié → F404 → slice [1:21]
- helpers `async def` non détectés par `def ` seul

A28 TERMINÉ en 4 lots : api_v2 (7.29.0), dashboard (7.30.0),
collections (7.31.0), board (7.32.0) — 0 changement d'URL sur les 4.

suite **1091/1091** · ruff OK · OpenAPI 509 identique · docs à jour

app/routers/board/__init__.py

@@ -0,0 +1,108 @@
+"""FlowDeck — Board : Kanban Notion-style + multi-vues.
+
+Découpe A28 : l'ancien `board.py` (2 101 lignes, 53 routes) est
+devenu ce package — un module par concern, helpers/constantes dans
+`_common`. Ré-exportés (importateurs inchangés) : api.py
+(STATUS_COLORS, STATUS_LABELS, _issue_column, _map_issue_to_card),
+webhooks (_issue_column), dashboard (_sidebar_data,
+_load_workspace_pages, _load_shared_sidebar_pages, _file_icon),
+tests (_build_page_tree, _REPO_REF_RE, _unfurl_repo).
+"""
+from __future__ import annotations
+
+import logging
+
+from fastapi import APIRouter
+
+from . import (  # ordre = ordre d'enregistrement d'origine
+    board_views,
+    embed,
+    import_,
+    library,
+    page_api,
+    page_media,
+    page_ops,
+    pages,
+    sharing,
+    sync,
+    synced,
+    wiki,
+)
+from ._common import (  # noqa: F401 — ré-exports
+    _REPO_REF_RE,
+    AI_KEYWORD_COLORS,
+    STATUS_COLORS,
+    STATUS_LABELS,
+    _apply_filters,
+    _apply_sorts,
+    _block_texts,
+    _build_page_tree,
+    _create_page_from_markdown,
+    _ensure_block_ids,
+    _ensure_page_editable,
+    _extract_ai_keywords,
+    _file_icon,
+    _get_project_properties,
+    _issue_column,
+    _load_children,
+    _load_shared_sidebar_pages,
+    _load_workspace_pages,
+    _local_workspaces_for_user,
+    _map_issue_to_card,
+    _record_version,
+    _sidebar_data,
+    _store_uploaded_file,
+    _unfurl_repo,
+    _upload_root,
+    _ws_id_for,
+    asyncio_get_labels,
+)
+
+logger = logging.getLogger(__name__)
+router = APIRouter()
+for _mod in (
+    wiki,
+    page_api,
+    library,
+    sharing,
+    synced,
+    board_views,
+    pages,
+    page_media,
+    import_,
+    embed,
+    page_ops,
+    sync,
+):
+    router.include_router(_mod.router)
+
+__all__ = [
+    "router",
+    "AI_KEYWORD_COLORS",
+    "STATUS_COLORS",
+    "STATUS_LABELS",
+    "_REPO_REF_RE",
+    "_apply_filters",
+    "_apply_sorts",
+    "_block_texts",
+    "_build_page_tree",
+    "_create_page_from_markdown",
+    "_ensure_block_ids",
+    "_ensure_page_editable",
+    "_extract_ai_keywords",
+    "_file_icon",
+    "_get_project_properties",
+    "_issue_column",
+    "_load_children",
+    "_load_shared_sidebar_pages",
+    "_load_workspace_pages",
+    "_local_workspaces_for_user",
+    "_map_issue_to_card",
+    "_record_version",
+    "_sidebar_data",
+    "_store_uploaded_file",
+    "_unfurl_repo",
+    "_upload_root",
+    "_ws_id_for",
+    "asyncio_get_labels",
+]