merge: integrate main into dev

Resolve 9 merge conflicts preserving both sides' intent:
- nix hash, bootstrap hostnames rename, websocket-server wiring
- session.ts handler dedup, snapshot fallback, worktree registration
- worktree-session git service + script/setup features
- sidebar-workspace-list setup navigation, session-context cleanup
- workspace-registry-bootstrap test kept (code still exists)
- checkout-git test additions from both sides

Post-merge fixes: isPaneFocused prop rename, server type rebuild.

packages/app/src/screens/agent/draft-agent-screen.tsx

@@ -1195,7 +1195,7 @@ function DraftAgentScreenContent({
             <Composer
               agentId={draftAgentIdRef.current}
               serverId={selectedServerId ?? ""}
-              isInputActive={isFocused}
+              isPaneFocused={isFocused}
               onSubmitMessage={handleCreateFromInput}
               isSubmitLoading={isSubmitting}
               blurOnSubmit={true}