* feat(darwin): add interactive terminal password prompt for keychain unlock (#556)
* test: add unit tests for keyretriever and address review feedback
- Add errStorageNotFound sentinel error for precise error matching
- Non-TTY TerminalPasswordRetriever returns nil silently (review #558)
- Add darwin tests: findStorageKey, empty password, non-TTY skip
- Add linux tests: FallbackRetriever peanuts key, DefaultRetriever chain
* fix: add nolint:unused for errStorageNotFound on Windows, clean up error message
errStorageNotFound is only used on darwin/linux; Windows lint flagged it
as unused. Also simplify error format to avoid "storage" duplication.
* fix: add nolint:unused for errStorageNotFound, simplify error message
errStorageNotFound is only referenced on darwin and linux; Windows lint
flags it as unused. Also remove redundant "storage" prefix from the
error format string.
Share a single KeyRetriever instance across all profiles of the same
browser, and add sync.Once caching to GcoredumpRetriever and
SecurityCmdRetriever. This avoids repeated keychain password prompts
(or securityd memory dumps) when extracting multiple profiles.
Closes#544