fix: budget save error and add read-only view mode (v2026.03.10)

Fix budget save 500 error caused by three data mismatches between
frontend and backend: wrapped payload ({lines:[...]}) vs expected
raw array, snake_case vs camelCase field names (account_id vs
accountId), and dec_amt vs dec for December values.

Add read-only budget view as default for existing budgets with an
"Edit Budget" button to enter edit mode, and Cancel to discard
changes - reducing accidental edits.

Bump version to 2026.03.10 across all packages and settings.

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

backend/src/main.ts

@@ -67,7 +67,7 @@ async function bootstrap() {
   const config = new DocumentBuilder()
     .setTitle('HOA LedgerIQ API')
     .setDescription('API for the HOA LedgerIQ')
-    .setVersion('2026.3.7')
+    .setVersion('2026.03.10')
     .addBearerAuth()
     .build();
   const document = SwaggerModule.createDocument(app, config);