OCR fix and Mobile QR changes (#5433)

# Description of Changes
## OCR / Tesseract path handling

Makes tessDataPath resolution deterministic with priority: config >
TESSDATA_PREFIX env > default.
Updates language discovery to use runtimePathConfig.getTessDataPath()
instead of raw config value.
Ensure default OCR dir is debian based not alpine

## Mobile scanner: feature gating + new conversion settings
Adds system.mobileScannerSettings (convert-to-PDF + resolution + page
format + stretch) exposed via backend config and configurable in the
proprietary admin UI.
Enforces enableMobileScanner on the MobileScannerController endpoints
(403 when disabled).
Frontend mobile upload flow can now optionally convert received images
to PDF (pdf-lib + canvas).

## Desktop/Tauri connectivity work
Expands tauri-plugin-http permissions and enables dangerous-settings.
Adds a very comprehensive multi-stage server connection diagnostic
routine (with lots of logging).


<img width="688" height="475" alt="image"
src="https://github.com/user-attachments/assets/6f9c1aec-58c7-449b-96b0-52f25430d741"
/>


---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### Translations (if applicable)

- [ ] I ran
[`scripts/counter_translation.py`](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/docs/counter_translation.md)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

scripts/init.sh

@@ -68,36 +68,28 @@ fi
 
 # # === tessdata ===
 # # Prepare Tesseract OCR data directory.
-REAL_TESSDATA="/usr/share/tesseract-ocr/5/tessdata"
-SEC_TESSDATA="/usr/share/tessdata"
+# In Debian, tesseract looks in /usr/share/tesseract-ocr/5/tessdata
+# For backwards compatibility, copy any user-mounted files from /usr/share/tessdata
+TESSDATA_SYSTEM="/usr/share/tesseract-ocr/5/tessdata"
+TESSDATA_MOUNT="/usr/share/tessdata"
 
 log_warn() {
   echo "[init][warn] $*" >&2
 }
 
-if [ -d "$REAL_TESSDATA" ] && [ -w "$REAL_TESSDATA" ]; then
-  log_warn "Skipping tessdata adjustments; directory writable: $REAL_TESSDATA"
-else
-  log_warn "Skipping tessdata adjustments; directory missing or not writable: $REAL_TESSDATA"
+# Ensure system tessdata directory exists
+mkdir -p "$TESSDATA_SYSTEM" 2>/dev/null || true
+
+# For backwards compatibility: if user mounted custom languages to /usr/share/tessdata,
+# copy them to the system location where Tesseract actually looks
+if [ -d "$TESSDATA_MOUNT" ] && [ "$(ls -A "$TESSDATA_MOUNT" 2>/dev/null)" ]; then
+  log_warn "Found user-mounted tessdata in $TESSDATA_MOUNT, copying to system location $TESSDATA_SYSTEM"
+  cp -rn "$TESSDATA_MOUNT"/* "$TESSDATA_SYSTEM"/ 2>/dev/null || true
 fi
 
-if [ -d /usr/share/tesseract-ocr/5/tessdata ]; then
-  REAL_TESSDATA="/usr/share/tesseract-ocr/5/tessdata"
-  log_warn "Using /usr/share/tesseract-ocr/5/tessdata as TESSDATA_PREFIX"
-elif [ -d /usr/share/tessdata ]; then
-  REAL_TESSDATA="/usr/share/tessdata"
-  log_warn "Using /usr/share/tessdata as TESSDATA_PREFIX"
-elif [ -d /tessdata ]; then
-  REAL_TESSDATA="/tessdata"
-  log_warn "Using /tessdata as TESSDATA_PREFIX"
-else
-  REAL_TESSDATA=""
-  log_warn "No tessdata directory found"
-fi
-
-if [ -n "$REAL_TESSDATA" ]; then
-  export TESSDATA_PREFIX="$REAL_TESSDATA"
-fi
+# Set TESSDATA_PREFIX to system location
+export TESSDATA_PREFIX="$TESSDATA_SYSTEM"
+log_warn "Using TESSDATA_PREFIX=$TESSDATA_PREFIX"
 
 # === Temp dir ===
 # Ensure the temporary directory exists and has proper permissions.