Sweep: Replace bare `string` NodeId typings in src/platform/

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

Replace bare \`nodeId: string\` typings in the platform layer with the canonical \`NodeId\` type, importing from \`@/platform/workflow/validation/schemas/workflowSchema\` (the platform-layer re-export of the canonical type from \`@/lib/litegraph/src/LGraphNode\`).

## Scope (13 files — missingMedia / missingModel / nodeReplacement / assets)

- \`src/platform/assets/schemas/assetMetadataSchema.ts\`
- \`src/platform/missingMedia/components/MissingMediaCard.vue\`
- \`src/platform/missingMedia/components/MissingMediaRow.vue\`
- \`src/platform/missingMedia/composables/useMissingMediaInteractions.ts\`
- \`src/platform/missingMedia/missingMediaStore.ts\`
- \`src/platform/missingModel/components/MissingModelCard.vue\`
- \`src/platform/missingModel/components/MissingModelRow.vue\`
- \`src/platform/missingModel/composables/useMissingModelInteractions.ts\`
- \`src/platform/missingModel/missingModelStore.ts\`
- \`src/platform/nodeReplacement/components/SwapNodeGroupRow.vue\`
- \`src/platform/nodeReplacement/components/SwapNodesCard.vue\`
- \`src/platform/nodeReplacement/missingNodesErrorStore.ts\`
- \`src/platform/nodeReplacement/types.ts\`

## Acceptance

- [ ] Every \`nodeId: string\` (and \`node_id: string\`) in the listed files swapped to \`NodeId\`
- [ ] \`pnpm typecheck\` passes
- [ ] Vue prop types use \`PropType\` or the destructured Vue 3.5 syntax with the \`NodeId\` type
- [ ] PR diff stays under ~300 LOC of non-test code

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-11841-Sweep-Replace-bare-string-NodeId-typings-in-src-platform-3546d73d365081468272edc9cac8301c) by [Unito](https://www.unito.io)