Add --shared flag to bd hooks install for versioned hooks

Implements support for installing git hooks to a versioned directory
(.beads-hooks/) that can be committed to the repository and shared with
team members. This solves the team collaboration issue where hooks need
to be installed in pre-built containers.

Changes:
- Add --shared flag to 'bd hooks install' command
- Install hooks to .beads-hooks/ when --shared is used
- Automatically configure git config core.hooksPath
- Update help text to explain shared mode

Fixes #229

.beads-hooks/pre-commit

@@ -0,0 +1,44 @@
+#!/bin/sh
+# bd-hooks-version: 0.24.2
+#
+# bd (beads) pre-commit hook
+#
+# This hook ensures that any pending bd issue changes are flushed to
+# .beads/beads.jsonl before the commit is created, preventing the
+# race condition where daemon auto-flush fires after the commit.
+#
+# Installation:
+#   cp examples/git-hooks/pre-commit .git/hooks/pre-commit
+#   chmod +x .git/hooks/pre-commit
+#
+# Or use the install script:
+#   examples/git-hooks/install.sh
+
+# Check if bd is available
+if ! command -v bd >/dev/null 2>&1; then
+    echo "Warning: bd command not found, skipping pre-commit flush" >&2
+    exit 0
+fi
+
+# Check if we're in a bd workspace
+if [ ! -d .beads ]; then
+    # Not a bd workspace, nothing to do
+    exit 0
+fi
+
+# Flush pending changes to JSONL
+# Use --flush-only to skip git operations (we're already in a git hook)
+# Suppress output unless there's an error
+if ! bd sync --flush-only >/dev/null 2>&1; then
+    echo "Error: Failed to flush bd changes to JSONL" >&2
+    echo "Run 'bd sync --flush-only' manually to diagnose" >&2
+    exit 1
+fi
+
+# Stage both possible JSONL files (backward compatibility)
+# git add is harmless if file doesn't exist
+for f in .beads/beads.jsonl .beads/issues.jsonl; do
+    [ -f "$f" ] && git add "$f" 2>/dev/null || true
+done
+
+exit 0