Store all mode results (OCR, Describe, Freeform) in a single job record

- DB: add describe_text and freeform_text columns (ALTER TABLE IF NOT EXISTS)
- Backend: commit and review endpoints accept/persist all three text fields
- App: accumulate results per mode in state; tabs appear when >1 mode run;
  all results sent on Commit Job
- JobDetail: tabbed text panel shows whichever fields are populated, all editable

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/database.py

@@ -45,6 +45,15 @@ def init_db():
             cur.execute("""
                 CREATE INDEX IF NOT EXISTS ocr_jobs_submitted_at_idx ON ocr_jobs(submitted_at DESC)
             """)
+            # Add columns introduced after initial schema (safe to run repeatedly)
+            cur.execute("""
+                ALTER TABLE ocr_jobs
+                ADD COLUMN IF NOT EXISTS describe_text TEXT
+            """)
+            cur.execute("""
+                ALTER TABLE ocr_jobs
+                ADD COLUMN IF NOT EXISTS freeform_text TEXT
+            """)
             # Unique constraint: prevent duplicate (author, chapter, page) submissions.
             # Applies only when all three fields are non-null.
             cur.execute("""