chore(config): track .claude/settings.json in version control

Settings.json is the shared team config (distinct from settings.local.json
which remains per-user). Remove it from .gitignore so it's tracked.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.claude/settings.json

@@ -0,0 +1,6 @@
+{
+  "env": {
+    "CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS": "1"
+  },
+  "teammateMode": "in-process"
+}

.gitignore

@@ -27,8 +27,7 @@ Thumbs.db
 *.swp
 *.swo
 
-# Claude Code internals (plans, session transcripts, local settings)
-# Note: .claude/agents/ and .claude/skills/ ARE tracked
+# Claude Code internals (plans, session transcripts)
+# Note: .claude/agents/, .claude/skills/, and .claude/settings.json ARE tracked
 .claude/plans/
 .claude/projects/
-.claude/settings.json