Follow-up: Quick Rename Unicode dropdown selection still degrades text / extension handling

[0xeb]

Summary

Issue #38 was partially fixed, but Quick Rename still has Unicode regressions when interacting with history/dropdown entries.

Current behavior

• In Quick Rename (F2), Unicode names can appear correctly in the dropdown list.
• After selecting a Unicode dropdown item, the edit box can show ??? instead of the selected Unicode text.
• In affected cases, extension handling can become inconsistent (e.g. apparent truncation in panel rendering / confusing already exists result when the target should be distinct).

Expected behavior

• Selecting a Unicode entry from rename history should preserve exact Unicode text in the edit control.
• Extension parsing/rendering should stay stable (no truncation artifacts).
• Retry flow should keep user-entered Unicode text and perform exact-path rename checks.

Repro (from current testing)

1. Create/select a file with Unicode name (e.g. Chinese/Korean characters).
2. Press F2 to open Quick Rename.
3. Open history dropdown and pick a Unicode history item.
4. Observe edit box content and attempt rename.

Notes

• Copy/paste and several rename paths were improved in 1.0.1 feedback from testing #38, but this remaining combo-selection/edit synchronization path still needs follow-up.
• This issue tracks the remaining Unicode rename/history/dropdown edge cases after 1.0.1 feedback from testing #38.