feat: optimize ag and apt snippet collections

AG (The Silver Searcher):
- Remove old snippets (5 removed)
- Add comprehensive search commands (38 added)
- Cover: search modes, output formats, file types, filters

APT (Debian/Ubuntu package manager):
- Remove old snippets (10 removed)
- Add comprehensive package commands (36 added)
- Cover: update/upgrade, install/remove, search, sources, dependencies

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Alfred.alfredpreferences/snippets/ag/ag -C 關鍵字 [C9D0E1F2-6A3B-5C6D-7E8F-9A0B1C2D3E4F].json

@@ -0,0 +1,8 @@
+{
+  "alfredsnippet" : {
+    "snippet" : "ag -C \"\"",
+    "uid" : "C9D0E1F2-6A3B-5C6D-7E8F-9A0B1C2D3E4F",
+    "name" : "顯示符合前後各 3 行",
+    "keyword" : ""
+  }
+}