feat: implement Trello board management

Add 5 board management tools extending the Trello client:
- trello_create_board — create a new board
- trello_rename_board — rename an existing board
- trello_archive_board — close/archive a board
- trello_open_board — re-open a closed board
- trello_board_details — view board with lists and members

Includes board name-to-ID resolution, 16 new tests, and spec doc.

Issue: #2

src/trello_plugin/__init__.py

@@ -8,8 +8,13 @@ from trello_plugin.tools import (
     PLUGIN_TOOLS,
     PLUGIN_VERSION,
     check_requirements,
+    trello_archive_board,
+    trello_board_details,
+    trello_create_board,
     trello_disconnect,
     trello_list_boards,
+    trello_open_board,
+    trello_rename_board,
     trello_verify_credentials,
 )
 
@@ -22,4 +27,9 @@ __all__ = [
     "trello_verify_credentials",
     "trello_list_boards",
     "trello_disconnect",
+    "trello_create_board",
+    "trello_rename_board",
+    "trello_archive_board",
+    "trello_open_board",
+    "trello_board_details",
 ]