Fix path completion hanging and autocomplete arrow key behavior

- Fixed catastrophic regex backtracking in extractPathPrefix that caused
  terminal to hang when text contained many / characters (e.g., URLs).
  Replaced complex regex with simple lastIndexOf approach. (#18)
- Fixed arrow keys moving both autocomplete selection and editor cursor
  by adding missing return statement after handling arrow keys in
  autocomplete mode.

Closes #18

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,13 @@
 
 ## [Unreleased]
 
+## [0.8.5] - 2025-11-21
+
+### Fixed
+
+- **Path Completion Hanging**: Fixed catastrophic regex backtracking in path completion that caused the terminal to hang when text contained many `/` characters (e.g., URLs). Replaced complex regex with simple string operations. ([#18](https://github.com/badlogic/pi-mono/issues/18))
+- **Autocomplete Arrow Keys**: Fixed issue where arrow keys would move both the autocomplete selection and the editor cursor simultaneously when the file selector list was shown.
+
 ## [0.8.4] - 2025-11-21
 
 ### Fixed