Make texture and colour full kinds and drop the load-time migrations

- `Texture` and `Color` can be picked as a variable kind, a struct field
  kind and a declared port kind; a new `Texture` node hands a picture id
  into the graph. Declared, a texture is its bare id – the `$texture` tag
  stays a list-only thing.
- The `String` node is labelled "Text" like its kind; the type id stays.
- Whole-number inputs (`Item at`, `Set item`, `Sub list`, `Fill`,
  `Repeat`, `Substring`, `To text`) show no decimals (`int()` in shared.ts).
- All server projects are reseeded, so `legacyNodes.ts`,
  `migrateDeclaredLists` and the `ownerId` fallback go, with their tests.
- Note `reseed-because-of-list` moved to done/; new note `refactor-types`.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/core/graph/nodes/data/Substring.ts

@@ -1,6 +1,6 @@
 import type { NodeDef } from '../../NodeRegistry';
 import { asNumber, asString } from '../../values';
-import { num, str, withDefault } from '../shared';
+import { int, str } from '../shared';
 
 export const Substring: NodeDef = {
   type: 'Substring',
@@ -9,7 +9,7 @@ export const Substring: NodeDef = {
   description:
     'A part of a text: "count" characters starting at "start" (the first is 0). ' +
     'A negative count reaches to the end.',
-  inputs: [str('text'), num('start'), withDefault(num('count'), -1)],
+  inputs: [str('text'), int('start'), int('count', -1)],
   outputs: [str('text')],
   params: [],
   run: (_ctx, inputs) => {