Set GIT_AUTHOR_NAME per agent session (gt-6r18e.1)

Export GIT_AUTHOR_NAME alongside BD_ACTOR in all agent session startup
locations. This enables git log --author queries for agent work while
keeping GIT_AUTHOR_EMAIL as the workspace owner.

Files updated:
- internal/session/manager.go (polecat sessions)
- internal/daemon/daemon.go (deacon, witness, polecat via daemon)
- internal/daemon/lifecycle.go (polecat lifecycle)
- internal/cmd/*.go (crew, mayor, deacon, witness, refinery, up, handoff)
- internal/session/manager_test.go (updated test expectations)
- docs/federation.md (marked feature as implemented)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/cmd/deacon.go

@@ -193,7 +193,7 @@ func startDeaconSession(t *tmux.Tmux) error {
 	// Restarts are handled by daemon via ensureDeaconRunning on each heartbeat
 	// The startup hook handles context loading automatically
 	// Export GT_ROLE and BD_ACTOR in the command since tmux SetEnvironment only affects new panes
-	if err := t.SendKeys(DeaconSessionName, "export GT_ROLE=deacon BD_ACTOR=deacon && claude --dangerously-skip-permissions"); err != nil {
+	if err := t.SendKeys(DeaconSessionName, "export GT_ROLE=deacon BD_ACTOR=deacon GIT_AUTHOR_NAME=deacon && claude --dangerously-skip-permissions"); err != nil {
 		return fmt.Errorf("sending command: %w", err)
 	}