feat: add external knowledge retrieval and cross-project activity

Connect Dify, FastGPT and RAGFlow through read-only bindings, encrypted local credentials, shared retrieval and persistent citations. Configuration and removal affect GoodBuddy only.

Show active conversations across projects, retain older live work, and improve project dialog scrolling. Queue concurrent questions and route managed SSH OpenCode questions through the Agent. Preserve recoverable read/search errors and partial search results.

Document the Electron UI automation standard, real model and external knowledge validation, and remaining acceptance limits.

Validation: earlier full regression passed 4081 tests with 66 skipped; subsequent focused remote-question checks and real Linux evidence are recorded in feature progress. Precommit typecheck and lint passed; latest project dialog and shared UI suites passed 58 tests. The full suite was not rerun for the final dialog changes.

Release note: Use external knowledge in conversations, find active work across projects, and answer concurrent local or managed SSH OpenCode questions. Managed SSH questions require the updated Agent adapter.

FEATURES.md

@@ -282,7 +282,9 @@ otherwise.
   pages; the selected model's context window and bounded transports still apply.
 - [x] **Native Runtime interaction routing**: OpenCode and Continue questions
   support choices, yes/no, free-text answers, and skipping through the existing
-  question card. OpenCode also routes questions from owned child sessions.
+  question card. Local and managed SSH OpenCode also route questions from
+  owned child sessions. Managed SSH requires the Agent question adapter;
+  this does not extend question support to arbitrary ACP services.
   Successful answers and skips retain the original questions and answers
   across rounds and local conversation reloads; answers discarded by older
   versions cannot be recovered.