feat: multi-Oracle server support with runtime switching

Complete implementation of multi-server Oracle database support:

Backend:
- Multi-pool Oracle with lazy loading per server
- Email-to-server cache for automatic server discovery
- JWT tokens include server_id claim
- /auth/check-identity and /auth/check-email endpoints
- /auth/my-servers endpoint for listing user's accessible servers
- Server switch with password re-authentication

Frontend:
- New ServerSelector component for header dropdown
- Multi-step login flow (identity → server → password)
- Server switching from header with password modal
- Mobile drawer menu with server selection
- Dark mode support for all new components
- URL bookmark support with ?server= query param

Scripts:
- Unified start.sh replacing start-prod.sh/start-test.sh
- Unified ssh-tunnel.sh with multi-server support
- Updated status.sh for new architecture

Tests:
- E2E tests for multi-server and single-server login flows
- Backend unit tests for all new endpoints
- Oracle multi-pool integration tests

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

backend/modules/data_entry/services/ocr/job_queue.py

@@ -61,6 +61,9 @@ DEFAULT_FILES_DIR = DEFAULT_QUEUE_DIR / "files"
 # Job expiration
 JOB_EXPIRY_HOURS = 24
 
+# SQLite busy timeout (milliseconds) - prevents "database is locked" errors
+SQLITE_BUSY_TIMEOUT_MS = 5000
+
 
 class OCRJobStatus(str, Enum):
     """Job status enum."""
@@ -152,6 +155,10 @@ class OCRJobQueue:
 
         # Create database and tables
         async with aiosqlite.connect(str(self.db_path)) as db:
+            # Enable WAL mode for better concurrency and set busy timeout
+            await db.execute("PRAGMA journal_mode=WAL")
+            await db.execute(f"PRAGMA busy_timeout={SQLITE_BUSY_TIMEOUT_MS}")
+
             await db.execute('''
                 CREATE TABLE IF NOT EXISTS ocr_jobs (
                     id TEXT PRIMARY KEY,
@@ -262,6 +269,7 @@ class OCRJobQueue:
 
         # Insert job record
         async with aiosqlite.connect(str(self.db_path)) as db:
+            await db.execute(f"PRAGMA busy_timeout={SQLITE_BUSY_TIMEOUT_MS}")
             await db.execute('''
                 INSERT INTO ocr_jobs (
                     id, status, file_path, mime_type, engine,
@@ -302,6 +310,7 @@ class OCRJobQueue:
         await self.initialize()
 
         async with aiosqlite.connect(str(self.db_path)) as db:
+            await db.execute(f"PRAGMA busy_timeout={SQLITE_BUSY_TIMEOUT_MS}")
             db.row_factory = aiosqlite.Row
             async with db.execute(
                 'SELECT * FROM ocr_jobs WHERE id = ?',
@@ -325,6 +334,7 @@ class OCRJobQueue:
         await self.initialize()
 
         async with aiosqlite.connect(str(self.db_path)) as db:
+            await db.execute(f"PRAGMA busy_timeout={SQLITE_BUSY_TIMEOUT_MS}")
             # Check if job is pending
             async with db.execute(
                 'SELECT status, created_at FROM ocr_jobs WHERE id = ?',
@@ -359,6 +369,7 @@ class OCRJobQueue:
 
         async with self._lock:  # Serialize access to prevent race conditions
             async with aiosqlite.connect(str(self.db_path)) as db:
+                await db.execute(f"PRAGMA busy_timeout={SQLITE_BUSY_TIMEOUT_MS}")
                 db.row_factory = aiosqlite.Row
 
                 # Get the next pending job
@@ -451,6 +462,7 @@ class OCRJobQueue:
             params = (status.value, job_id)
 
         async with aiosqlite.connect(str(self.db_path)) as db:
+            await db.execute(f"PRAGMA busy_timeout={SQLITE_BUSY_TIMEOUT_MS}")
             cursor = await db.execute(query, params)
             await db.commit()
             return cursor.rowcount > 0
@@ -467,6 +479,7 @@ class OCRJobQueue:
         await self.initialize()
 
         async with aiosqlite.connect(str(self.db_path)) as db:
+            await db.execute(f"PRAGMA busy_timeout={SQLITE_BUSY_TIMEOUT_MS}")
             async with db.execute('''
                 SELECT AVG(processing_time_ms)
                 FROM (
@@ -486,6 +499,7 @@ class OCRJobQueue:
         await self.initialize()
 
         async with aiosqlite.connect(str(self.db_path)) as db:
+            await db.execute(f"PRAGMA busy_timeout={SQLITE_BUSY_TIMEOUT_MS}")
             async with db.execute(
                 'SELECT COUNT(*) FROM ocr_jobs WHERE status = ?',
                 (OCRJobStatus.pending.value,)
@@ -498,6 +512,7 @@ class OCRJobQueue:
         await self.initialize()
 
         async with aiosqlite.connect(str(self.db_path)) as db:
+            await db.execute(f"PRAGMA busy_timeout={SQLITE_BUSY_TIMEOUT_MS}")
             async with db.execute(
                 'SELECT COUNT(*) FROM ocr_jobs WHERE status = ?',
                 (OCRJobStatus.processing.value,)
@@ -518,6 +533,7 @@ class OCRJobQueue:
         deleted = 0
 
         async with aiosqlite.connect(str(self.db_path)) as db:
+            await db.execute(f"PRAGMA busy_timeout={SQLITE_BUSY_TIMEOUT_MS}")
             db.row_factory = aiosqlite.Row
 
             # Get expired jobs
@@ -588,6 +604,7 @@ class OCRJobQueue:
         }
 
         async with aiosqlite.connect(str(self.db_path)) as db:
+            await db.execute(f"PRAGMA busy_timeout={SQLITE_BUSY_TIMEOUT_MS}")
             async with db.execute('''
                 SELECT status, COUNT(*) as count
                 FROM ocr_jobs