docs: fix GitHub demo 500 by reading the playground LibrarySpec

[devin-ai-integration]

What

openui.com/demo/github returns Error: Server error 500 on every generation. The route crashes at module init: generatePrompt() throws Cannot convert undefined or null to object on Object.values(spec.components).

Root cause: the route read generated/playground-component-spec.json, which is produced by openui generate --json-schema. Since #1095 regenerated it, that flag emits a raw JSON Schema ({ $schema, type, properties, $defs }) instead of a PromptSpec-shaped object, so spec.components is undefined.

Changes

• Read generated/playground-system-prompt.spec.json (the LibrarySpec sidecar the playground prompt step already emits: { root, components, componentGroups, schema }) instead.
• Remove the --json-schema step from generate:prompts and delete the stale playground-component-spec.json, so there is a single source for the playground spec.

Test Plan

• Verified locally: generatePrompt({...spec, tools, editMode, ...}) throws with the old file and produces a 28.9k-char prompt with the new file.
• prettier --check and eslint clean on changed files.
• Reproduced the 500 on prod (POST /api/demo/github/stream returns empty 500; /api/playground/stream reaches OpenRouter fine, so the key/env is not the issue).

Checklist

• I considered backwards compatibility (no public API change; internal generated asset only)

Link to Devin session: https://app.devin.ai/sessions/ad40852cdb2f4b2495d98767eed82628
Open in Devin Desktop: https://app.devin.ai/desktop/session/ad40852cdb2f4b2495d98767eed82628?variant=devin
Requested by: @zahlekhan

[devin-ai-integration]

I'll fix CI failures and address comments from users with write access. I'll skip comments containing "(aside)".

• Disable automatic comment, CI, and merge conflict monitoring

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Project	Deployment	Actions	Updated
openui-docs	Ready	Preview	Sep 22, 2026 7:14am UTC

[devin-ai-integration]

Superseded by #1222, which switched the route to playground-library.spec.json + generateSystemPrompt. Prod /api/demo/github/stream now returns 200.