Sync ECA integration with latest upstream bridge and ext changes

Co-authored-by: tninja <714625+tninja@users.noreply.github.com>

Author: Copilot

HISTORY.org

@@ -2,6 +2,7 @@
 * Release history
 
 ** Main branch change
+- Feat: Sync ECA integration with latest upstream bridge/ext changes: workspace management, auto project/session syncing, shared context helpers, and session health utilities
 - Feat: Improve ECA backend: smarter chat-buffer handling, graceful resume, context management (file/clipboard/cursor/repo-map), session multiplexing via eca-ext.el, upgrade and install-skills support, contributed by davidwuchn
 - Fix: Block ai-code-apply-prompt-on-current-file for eca backend (like agent-shell)
 - Feat: Add ECA (https://eca.dev/) as an external backend, contributed by davidwuchn

README.org

@@ -242,6 +242,7 @@ When working with multiple AI sessions, it can be useful to receive desktop noti
      (ai-code-set-backend 'eca)
      #+end_src
      Optionally, load =[[./eca-ext.el][eca-ext.el]]= (bundled with this package) for session multiplexing
+     plus workspace management, auto project/session syncing, shared context,
      and programmatic context management (file, clipboard, cursor, repo-map):
      #+begin_src emacs-lisp
      (require 'eca-ext)