[FEATURE] Prioritize active VSCode editor file in @ mention file picker

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

When using @ to mention a file, the picker presents a flat list with no awareness of the currently active editor. In projects with multiple identically-named files across subdirectories (e.g., several SESSION_CONTEXT.md files), the user must manually disambiguate every time, even when the file they want is already open in the editor.

Proposed Solution

Surface the currently active editor file as the first result in the @ file picker, ahead of any fuzzy-matched suggestions. The active file is already available via the VS Code API, so this should be low-cost to implement.

Alternative Solutions

_No response_

Priority

Medium - Would be very helpful

Feature Category

CLI commands and flags

Use Case Example

A user working in a multi-project repo has PROJECT_A/SESSION_CONTEXT.md open in their editor. They type @SESSION and are presented with five files named SESSION_CONTEXT.md from different subdirectories. They have to read the full paths to find the right one. If the active editor file were prioritized, the correct file would simply be the first result.

Additional Context

_No response_