fix(deps): improve parent-child dependency UX (GH #440)

- Fix DEPENDENCIES.md: correct parent-child syntax (child depends on parent)
- Update bd show: display Children instead of Blocks for parent-child deps
- Group dependents by type with distinct labels

Generated with Claude Code

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

.beads/deletions.jsonl

@@ -0,0 +1,3 @@
+{"id":"bd-3pd","ts":"2025-12-02T05:05:53.732197Z","by":"stevey","reason":"batch delete"}
+{"id":"bd-ksc","ts":"2025-12-02T05:05:53.742343Z","by":"stevey","reason":"batch delete"}
+{"id":"bd-360","ts":"2025-12-02T05:05:53.74642Z","by":"stevey","reason":"batch delete"}