add special variable: ${^LAST_SUCCESSFUL_PATTERN}

Author: fglock

MILESTONES.md

@@ -313,7 +313,7 @@ The following areas are currently under active development to enhance the functi
 
 - **v5.42.2**: Next minor version
 
-  - Add special variable `@{^CAPTURE}`.
+  - Add special variables: `@{^CAPTURE}`, `${^LAST_SUCCESSFUL_PATTERN}`.
   - Planned release date: 2025-12-10.
 
 - Work in Progress

docs/FEATURE_MATRIX.md

@@ -252,7 +252,7 @@ my @copy = @{$z};         # ERROR
 - ✅  **lvalue `pos`**: lvalue `pos` operator is implemented.
 - ✅  **`m?pat?`** one-time match is implemented.
 - ✅  **`reset`** resetting one-time match is implemented
-- ✅  **`@-`, `@+`, `%+`, `%-`, `@{^CAPTURE}` variables**: regex special variables are implemented
+- ✅  **`@-`, `@+`, `%+`, `%-`, `@{^CAPTURE}`, `${^LAST_SUCCESSFUL_PATTERN}` variables**: regex special variables are implemented
 - ✅  **`$&` variables**: `` $` ``, `$&`, `$'`, `$+` special variables are implemented, and aliases: `${^PREMATCH}`, `${^MATCH}`, `${^POSTMATCH}`.
 - ✅  **`[[:pattern:]]`**: `[[:ascii:]]`, `[[:print:]]` are implemented.
 - ✅  **Matching plain strings**: `$var =~ "Test"` is implemented.