fix: auto-foreground brainstorm server on Windows/Git Bash

Windows/Git Bash reaps nohup background processes, causing the brainstorm
server to die silently after launch. Auto-detect Windows via OSTYPE
(msys/cygwin/mingw) and MSYSTEM env vars, switching to foreground mode
automatically. Tested on Windows 11 from CMD, PowerShell, and Git Bash —
all route through Git Bash and hit the same issue.

Based on #740, fixes #737. Also adds CHANGELOG.md documenting the fix and
a known OWNER_PID/WINPID mismatch on the main branch.

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

skills/brainstorming/scripts/start-server.sh

@@ -64,6 +64,16 @@ if [[ -n "${CODEX_CI:-}" && "$FOREGROUND" != "true" && "$FORCE_BACKGROUND" != "t
   FOREGROUND="true"
 fi
 
+# Windows/Git Bash reaps nohup background processes. Auto-foreground when detected.
+if [[ "$FOREGROUND" != "true" && "$FORCE_BACKGROUND" != "true" ]]; then
+  case "${OSTYPE:-}" in
+    msys*|cygwin*|mingw*) FOREGROUND="true" ;;
+  esac
+  if [[ -n "${MSYSTEM:-}" ]]; then
+    FOREGROUND="true"
+  fi
+fi
+
 # Generate unique session directory
 SESSION_ID="$$-$(date +%s)"
 

skills/brainstorming/visual-companion.md

@@ -61,6 +61,14 @@ scripts/start-server.sh --project-dir /path/to/project
 scripts/start-server.sh --project-dir /path/to/project
 ```
 
+**Windows (Git Bash / CMD / PowerShell):**
+```bash
+# Windows/Git Bash reaps nohup background processes. The script auto-detects
+# this via OSTYPE/MSYSTEM and switches to foreground mode automatically.
+# No extra flags needed — all Windows shells route through Git Bash.
+scripts/start-server.sh --project-dir /path/to/project
+```
+
 **Gemini CLI:**
 ```bash
 # Use --foreground and set is_background: true on your shell tool call