site.standard.document: tags maxGraphemes and maxLength should be inside items #9

Hi all! First off, congrats on launching standard.site! I'm excited to see it come together, and to start working with it.

I noticed a possible bug in site.standard.document, at least in the current published version. tags has maxGraphemes and maxLength at its top level, but it looks like they're supposed to apply to the elements, so I think they should go inside items instead. See tags in app.bsky.feed.post as an example.

I tried to put a PR together to fix this, but I'm currently getting this error from bun x prototypey gen-emit ./out ./src/lexicons/**/*.ts, and I'm not familiar enough with this toolchain to debug it.

Found 5 source file(s)
  ✓ site.standard.document -> site.standard.document.json
  ✓ site.standard.graph.subscription -> site.standard.graph.subscription.json
  ✗ Error processing /Users/ryan/src/standard-site-lexicons/src/lexicons/site.standard.publication.ts: TypeError: Cannot use 'in' operator to search for 'required' in Platform-specific preferences for the publication, including discovery and visibility settings.
    at file:///Users/ryan/src/standard-site-lexicons/node_modules/prototypey/lib/core/lib.js:108:68
    at Array.filter (<anonymous>)
    at Object.object (file:///Users/ryan/src/standard-site-lexicons/node_modules/prototypey/lib/core/lib.js:108:41)
    at file:///Users/ryan/src/standard-site-lexicons/src/lexicons/site.standard.publication.ts:40:21
    at ModuleJob.run (node:internal/modules/esm/module_job:371:25)
    at async onImport.tracePromise.__proto__ (node:internal/modules/esm/loader:683:26)
    at async processSourceFile (file:///Users/ryan/src/standard-site-lexicons/node_modules/prototypey/lib/cli/gen-emit.js:29:18)
    at async genEmit (file:///Users/ryan/src/standard-site-lexicons/node_modules/prototypey/lib/cli/gen-emit.js:20:41)
Error emitting lexicon schemas: TypeError: Cannot use 'in' operator to search for 'required' in Platform-specific preferences for the publication, including discovery and visibility settings.
    at file:///Users/ryan/src/standard-site-lexicons/node_modules/prototypey/lib/core/lib.js:108:68
    at Array.filter (<anonymous>)
    at Object.object (file:///Users/ryan/src/standard-site-lexicons/node_modules/prototypey/lib/core/lib.js:108:41)
    at file:///Users/ryan/src/standard-site-lexicons/src/lexicons/site.standard.publication.ts:40:21
    at ModuleJob.run (node:internal/modules/esm/module_job:371:25)
    at async onImport.tracePromise.__proto__ (node:internal/modules/esm/loader:683:26)
    at async processSourceFile (file:///Users/ryan/src/standard-site-lexicons/node_modules/prototypey/lib/cli/gen-emit.js:29:18)
    at async genEmit (file:///Users/ryan/src/standard-site-lexicons/node_modules/prototypey/lib/cli/gen-emit.js:20:41)

cc @quillmatiq.com