improve redirects section (#559)

* fix redirect language code prefixes

* fix syntax in wildcard redirect links

* delete stale file & more redirect cosmetics

en/use-dify/nodes/rename-test-gamma.mdx

@@ -1,41 +0,0 @@
----
-title: Rename Test Alpha
-description: Complete validation of all three rename fixes
----
-
-# Rename Test Alpha
-
-This test validates all three critical fixes for the rename bug:
-
-## The Three Fixes
-
-**Fix #1 - Extension Stripping (Location Lookup)**:
-- Problem: `_handle_rename` looked up `"en/.../file.mdx"` but docs.json has `"en/.../file"`
-- Solution: Strip `.mdx`/`.md` before location lookup
-- Commit: 8bf899c6
-
-**Fix #2 - Conditional Rename Detection**:
-- Problem: Reconcile always skipped rename detection, treating R100 renames as delete+add
-- Solution: Only skip when git actually detected renames
-- Commit: 532e97cf
-
-**Fix #3 - Extension Stripping (New Target)**:
-- Problem: Added entries with extension like `"cn/.../file.mdx"` instead of `"cn/.../file"`
-- Solution: Strip extension before adding to docs.json
-- Commit: b9489a0a
-
-## Test Plan
-
-1. **Alpha** (this file) → Translated to cn/jp
-2. **Alpha → Beta** → Validate both physical files AND docs.json entries renamed
-3. **Beta → Gamma** → Validate consistency across multiple renames
-
-## Expected Results
-
-After each rename:
-- ✅ Physical files renamed: `cn/rename-test-*.mdx`, `jp/rename-test-*.mdx`
-- ✅ docs.json entries updated: `cn/.../rename-test-*` (no extension)
-- ✅ NO deletions of cn/jp entries
-- ✅ Entries match English structure exactly
-
-🤖 Generated by Claude Code for complete rename fix validation