Implement post editing functionality for Mastodon

Add ability to edit posts in Mastodon with full support for:
- Editing post text and content warnings
- Re-uploading or keeping existing media attachments
- Editing poll options (for posts with polls)
- Modifying visibility and language settings
- All features available through web interface

Changes:
- Add edit_post() method in Mastodon session to handle API calls
- Create editPost dialog class that loads existing post data
- Add edit_status() method to buffer controllers
- Add Edit menu item to base and notification menus
- Register edit_post action in all keymaps (no default key assigned)
- Add edit_post() action handler in main controller

The edit option is only enabled for the user's own posts (not boosts).
Users can access the feature through the context menu or by assigning
a keyboard shortcut in the keymap editor.

src/keymaps/Chicken Nugget.keymap

@@ -23,6 +23,7 @@ url = string(default="control+win+b")
 go_home = string(default="control+win+home")
 go_end = string(default="control+win+end")
 delete = string(default="control+win+delete")
+edit_post = string(default="")
 clear_buffer = string(default="control+win+shift+delete")
 repeat_item = string(default="control+win+space")
 copy_to_clipboard = string(default="control+win+shift+c")

src/keymaps/Qwitter.keymap

@@ -33,6 +33,7 @@ go_page_up = string(default="control+win+pageup")
 go_page_down = string(default="control+win+pagedown")
 update_profile = string(default="control+win+shift+p")
 delete = string(default="control+win+delete")
+edit_post = string(default="")
 clear_buffer = string(default="control+win+shift+delete")
 repeat_item = string(default="control+win+space")
 copy_to_clipboard = string(default="control+win+shift+c")

src/keymaps/Windows 10.keymap

@@ -33,6 +33,7 @@ go_page_up = string(default="control+win+pageup")
 go_page_down = string(default="control+win+pagedown")
 update_profile = string(default="alt+win+p")
 delete = string(default="alt+win+delete")
+edit_post = string(default="")
 clear_buffer = string(default="alt+win+shift+delete")
 repeat_item = string(default="alt+win+space")
 copy_to_clipboard = string(default="alt+win+shift+c")

src/keymaps/Windows11.keymap

@@ -33,6 +33,7 @@ go_page_up = string(default="control+win+pageup")
 go_page_down = string(default="control+win+pagedown")
 update_profile = string(default="alt+win+p")
 delete = string(default="alt+win+delete")
+edit_post = string(default="")
 clear_buffer = string(default="alt+win+shift+delete")
 repeat_item = string(default="control+alt+win+space")
 copy_to_clipboard = string(default="alt+win+shift+c")

src/keymaps/default.keymap

@@ -34,6 +34,7 @@ go_page_up = string(default="control+win+pageup")
 go_page_down = string(default="control+win+pagedown")
 update_profile = string(default="alt+win+p")
 delete = string(default="control+win+delete")
+edit_post = string(default="")
 clear_buffer = string(default="control+win+shift+delete")
 repeat_item = string(default="control+win+space")
 copy_to_clipboard = string(default="control+win+shift+c")