Add Print Queue UI and slicer post-processing script

- Create Print Queue page showing pending/completed/cancelled jobs
- Add needs_weighing filter to spool API for flagged spools
- Add IPrintJob interface and needs_weighing to ISpool model
- Add slicer_post_process.py for Elegoo/Orca Slicer integration
- Add translations for print queue feature
- Bump version to 0.23C.3

The workflow:
1. Slicer post-processing script creates pending print job
2. After print, user confirms (deducts filament) or cancels (flags for weighing)
3. Spools needing weigh-in are shown in Print Queue UI

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

client/public/locales/en/common.json

@@ -450,5 +450,53 @@
         "new_location": "New Location",
         "no_location": "No Location",
         "no_locations_help": "This page lets you organize your spools in locations, add some spools to get started!"
+    },
+    "print-queue": {
+        "print-queue": "Print Queue"
+    },
+    "print_queue": {
+        "title": "Print Queue",
+        "pending_jobs": "Pending Jobs",
+        "needs_weighing": "Spools Needing Weigh-In",
+        "recent_history": "Recent History",
+        "no_pending_jobs": "No pending print jobs",
+        "no_history": "No completed or cancelled jobs yet",
+        "fields": {
+            "filename": "Filename",
+            "spool": "Spool",
+            "filament_used": "Filament Used",
+            "created": "Created",
+            "finished": "Finished",
+            "status": "Status"
+        },
+        "status": {
+            "pending": "Pending",
+            "completed": "Completed",
+            "cancelled": "Cancelled"
+        },
+        "stats": {
+            "pending": "Pending",
+            "needs_weighing": "Need Weigh-In",
+            "completed_today": "Completed Today",
+            "total_jobs": "Total Jobs"
+        },
+        "complete": "Complete",
+        "cancel": "Cancel",
+        "cancel_job": "Cancel Job",
+        "weigh_in": "Weigh In",
+        "clear_flag": "Clear Flag",
+        "clear_flag_tooltip": "Mark as weighed without updating weight",
+        "confirm_complete": "Complete Print Job?",
+        "confirm_complete_description": "This will deduct {{grams}}g from the spool.",
+        "confirm_cancel": "Cancel Print Job?",
+        "confirm_cancel_description": "The spool will be flagged for manual weigh-in since filament usage is unknown.",
+        "confirm_delete": "Delete Print Job?",
+        "confirm_delete_description": "This will permanently remove this job from history.",
+        "job_completed": "Print job completed",
+        "job_complete_error": "Failed to complete print job",
+        "job_cancelled": "Print job cancelled - spool flagged for weigh-in",
+        "job_cancel_error": "Failed to cancel print job",
+        "job_deleted": "Print job deleted",
+        "weighing_cleared": "Weigh-in flag cleared"
     }
 }