Replace structuredClone with shape-aware clones in rundown/data hot paths

structuredClone's generic serialization algorithm does far more work than
plain object spreads need for these known shapes. Adds cloneEntryData()
and cloneRundown() as drop-in replacements (same "independent copy" contract,
same call sites) and swaps them in everywhere a rundown or a single entry
was being deep-cloned via structuredClone:

- createTransaction()/init() in rundown.dao.ts - the main per-mutation clone
- DataProvider.setRundown() - was re-cloning the whole rundown a second time
  on every single commit
- rundown.service.ts background-rundown clones (custom field rename/remove,
  duplicateExistingRundown)
- the per-entry clone in processRundown's non-mutating path (rundown.parser.ts)
- mergeRundownPreservingFields's per-entry clone

Also:
- safeMerge() (DataProvider.utils.ts) was deep-cloning the entire DatabaseModel,
  including all rundowns, just to read a handful of small config properties
  that never touch rundowns - it now only clones the properties it actually
  merges.
- sheets.service.ts's per-row clone before building a (read-only) Google
  Sheets cell request was unnecessary and is removed.
- runtime.service.ts's previous-state snapshot for eventNow/eventNext/
  eventFlag/groupNow now uses cloneEntryData.

Benchmarked on a synthetic 1000-event rundown: a cue-only edit (no
reprocessing needed) went from ~5ms to ~1.2ms end to end, including the
DataProvider clone. Verified against the existing test suite (695 passing)
plus typecheck and lint.

apps/server/src/services/runtime-service/runtime.service.ts

@@ -20,6 +20,7 @@ import { triggerAutomations } from '../../api-data/automation/automation.service
 import { triggerReportEntry } from '../../api-data/report/report.service.js';
 import { getCurrentRundown, getEntryWithId, getRundownMetadata } from '../../api-data/rundown/rundown.dao.js';
 import { RundownMetadata } from '../../api-data/rundown/rundown.types.js';
+import { cloneEntryData } from '../../api-data/rundown/rundown.utils.js';
 import { logger } from '../../classes/Logger.js';
 import { timerConfig } from '../../setup/config.js';
 import { eventStore } from '../../stores/EventStore.js';
@@ -754,7 +755,7 @@ function broadcastResult(_target: any, _propertyKey: string, descriptor: Propert
       }
       // at this point we know that either the id or the contents has changed
       batch.add(key, currentEntry as RuntimeStore[K]); // we know that there is the necessary overlap in the types to cast this
-      RuntimeService.previousState[key] = structuredClone(currentEntry);
+      RuntimeService.previousState[key] = currentEntry ? cloneEntryData(currentEntry) : null;
       return true;
     }