fix(hooks): add version markers to shim templates

cmd/bd/templates/hooks/post-checkout

@@ -1,5 +1,6 @@
 #!/bin/sh
 # bd-shim v1
+# bd-hooks-version: 0.31.0
 #
 # bd (beads) post-checkout hook - thin shim
 #

cmd/bd/templates/hooks/post-merge

@@ -1,5 +1,6 @@
 #!/bin/sh
 # bd-shim v1
+# bd-hooks-version: 0.31.0
 #
 # bd (beads) post-merge hook - thin shim
 #

cmd/bd/templates/hooks/pre-commit

@@ -1,5 +1,6 @@
 #!/bin/sh
 # bd-shim v1
+# bd-hooks-version: 0.31.0
 #
 # bd (beads) pre-commit hook - thin shim
 #

cmd/bd/templates/hooks/pre-push

@@ -1,5 +1,6 @@
 #!/bin/sh
 # bd-shim v1
+# bd-hooks-version: 0.31.0
 #
 # bd (beads) pre-push hook - thin shim
 #