fix(hooks): Route hook templates to Dolt-aware implementations

- Fix infinite recursion bug in computeJSONLHashForHook (was calling
  itself instead of computeJSONLHash)
- Update pre-commit, post-merge, post-checkout templates to use
  `bd hook <name>` instead of `bd hooks run <name>`, routing to the
  Dolt-aware implementations in hook.go
- Update all hook template versions to 0.48.0 for consistency

The hook infrastructure added in 15d74a9a had a critical bug where
the hash computation function recursed infinitely, and the templates
still pointed to the old hook implementations in hooks.go instead
of the new Dolt-aware ones in hook.go.

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

cmd/bd/templates/hooks/prepare-commit-msg

@@ -1,6 +1,6 @@
 #!/usr/bin/env sh
 # bd-shim v1
-# bd-hooks-version: 0.41.0
+# bd-hooks-version: 0.48.0
 #
 # bd (beads) prepare-commit-msg hook - thin shim
 #