Sweep: Replace bare `string` NodeId typings in stores / services / utils / scripts / types

Follow-up to #11428 (canonical type now landed in #11839).

Replace bare \`nodeId: string\` (and \`node_id: string\`) function parameters, fields, and getters with the canonical \`NodeId\` type imported from \`@/lib/litegraph/src/LGraphNode\` (or via the re-export from \`@/platform/workflow/validation/schemas/workflowSchema\`).

## Scope (11 files)

- \`src/stores/executionStore.ts\`
- \`src/stores/nodeOutputStore.ts\`
- \`src/stores/resultItemParsing.ts\`
- \`src/services/dialogService.ts\`
- \`src/services/litegraphService.ts\`
- \`src/services/subgraphPseudoWidgetCache.ts\`
- \`src/utils/graphTraversalUtil.ts\`
- \`src/utils/linkFixer.ts\`
- \`src/scripts/api.ts\`
- \`src/scripts/app.ts\`
- \`src/types/simplifiedWidget.ts\`

## Acceptance

- [ ] Every \`nodeId: string\` (and \`node_id: string\`) in the listed files swapped to \`NodeId\`
- [ ] \`pnpm typecheck\` passes
- [ ] PR diff stays under ~300 LOC of non-test code

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-11840-Sweep-Replace-bare-string-NodeId-typings-in-stores-services-utils-scripts--3546d73d36508172ab2cd42a1050c2ce) by [Unito](https://www.unito.io)