feat: prefer same-cwd entries for inline history suggestions

[ChanningHe]

Summary

Inline history suggestions now prefer commands previously run in the current directory, falling back to the most recent global match.

Behavior

• Scans the last 1000 history entries for a prefix match whose cwd equals the current directory; otherwise uses the most recent match as before.
• Only the JSONL history backend (flyline history --backend flyline) records cwd. With the bash backend, or entries imported from bash/zsh history, behavior is unchanged.

Configuration

flyline editor --inline-history-prefer global|cwd   # default: cwd
flyline editor --inline-history-prefer-window NUM   # default: 1000

--inline-history-prefer is an enum so other modes (session, host, workspace) can be added later without touching the history layer.

Implementation

• HistoryManager::get_command_suggestion_suffix takes an optional prefer predicate and a scan window; it no longer knows about cwd itself.
• App caches the shell cwd once at startup and maps the setting to a predicate.
• The window bounds the extra scan cost and keeps very old same-directory entries from beating recent global ones.

Testing

• Manually checked in bash with the JSONL backend.