[Bug] "Export Current" fails to append file extension from dropdown

[uthsabchakma]

When using the Export Current feature, selecting a format from the dropdown menu and clicking "Save" results in a silent failure. The application fails to append the appropriate file extension to the filename, causing the saving process to crash with an unknown file extension error.

Note:

• The "Export All Marked" function works as expected and correctly appends extensions.
• Manually typing the extension (e.g., image.jpg) into the filename field - solves the issue.

System Information

App Version: Raw-Alchemy Studio v0.5.0
OS: Fedora 43 (GNOME)

Steps to Reproduce

1. Open a RAW image (.RAF or .DNG).
2. Perform edits/adjustments.
3. Click on Export Current.
4. In the file picker, select a format from the dropdown (JPEG, DNG).
5. Click Save without manually typing .jpg (or .dng) in the filename.

Expected Behavior
The app should automatically append the extension based on the selected format in the dropdown (e.g., image_name becomes image_name.jpg).

Actual Behavior
The app attempts to save the file without an extension, leading to the following log error:
ERROR | [DSCF1630.RAF] ❌ Failed to save file: unknown file extension:

Logs
2026-04-01 15:15:28 | INFO | [DSCF1630.RAF] 🧪 [Raw Alchemy] Processing: ~/Pictures/Photos/Test_images/DSCF1630.RAF
2026-04-01 15:15:28 | INFO | [DSCF1630.RAF] 🔹 [Step 1] Decoding RAW...
2026-04-01 15:15:43 | INFO | [DSCF1630.RAF] 🔹 [Step 2] Manual Exposure Override (+3.70 stops)
2026-04-01 15:15:43 | INFO | [DSCF1630.RAF] 🔹 [Step 3.1] Lens Correction...
2026-04-01 15:15:43 | INFO | 🧬 [Lens] FUJIFILM X-T3 + XF23mmF2 R WR
2026-04-01 15:15:43 | INFO | 📷 [Lensfun] Using camera crop factor: 1.53
2026-04-01 15:15:43 | INFO | ⚖️ [Lensfun] Auto-scaling enabled with factor: 0.9896
2026-04-01 15:15:53 | INFO | [DSCF1630.RAF] 🔹 [Step 3.4] Saturation/Contrast (S:1.25, C:1.10)...
2026-04-01 15:15:53 | INFO | [DSCF1630.RAF] 🔹 [Step 4] Color Transform (ProPhoto -> ITU-R BT.2020 -> L-Log)
2026-04-01 15:15:55 | INFO | [DSCF1630.RAF] 🔹 [Step 5] Applying LUT L-Log_to_Classic_VLog.cube...
2026-04-01 15:15:55 | INFO | [DSCF1630.RAF] 🔹 [Step 5.6] Applying RL sharpening (strength=0.10)...
2026-04-01 15:15:55 | DEBUG | RL sharpening: sigma=1.0, iterations=1, strength=1.0
2026-04-01 15:15:57 | INFO | [DSCF1630.RAF] ✅ Sharpening complete
2026-04-01 15:15:57 | INFO | [DSCF1630.RAF] 💾 Saving to DSCF1630...
2026-04-01 15:15:57 | INFO | [DSCF1630.RAF] Format: (8-bit High Quality)
2026-04-01 15:15:57 | ERROR | [DSCF1630.RAF] ❌ Failed to save file: unknown file extension: