feat: clarify API guides and shorten the path to first usage

[runshouse]

Developers arriving from search encounter consumer-oriented guide titles and large media examples before the API links. Give 27 guides concise API titles, move reference/setup links before media, and provide the path from guide → API reference → quickstart → pricing → API key. Add the existing Postman guide to navigation and contextual links to models, account details, and starter recipes.

Fix 37 Node examples to pass workflow options as the second generate() argument, a Python voice-cloning syntax error, three malformed Python reference samples, unsupported GIF input claims, and the Windows quickstart's environment-variable command. Endpoint contracts and pricing are unchanged.

Validation on 61ac003: all three repository checks pass (broken links, API reference, webhook reference). 37 Node guide examples were checked against published SDK 0.75.0; 39 Python guide snippets and all 36 Python reference samples parse. A fixture test verified the corrected GIF helper's submission, polling, and download. Local preview compiled; hidden-browser clicks reached the actual Developer Hub API-key tab. No live generation, key creation, or completed signup was performed. No hosted deployment is available, and no automated Codex review result has appeared.

The generated-sample source fix Python SDK #167 is merged. Its 174 README snippets parse and five CI checks passed. web-app #14762 now applies the two corrected samples to the production code-sample source of truth; its repository and OpenAPI checks pass. Release #14762 first, verify the public OpenAPI payload, then merge this PR so later imports preserve the corrected Headshot and Photo Colorizer examples. Face Detection was already corrected upstream. No new test harness or generator behavior is added.

Release sequence:

1. David approves the current heads of web-app #14762 (5b7d80f) and this PR (61ac003). Do not treat an earlier-head approval as current.
2. Merge web-app #14762 after approval; deploy it through the standard production release path.
3. Fetch https://magichour.ai/docs/api/openapi.json and parse every Python x-codeSamples entry. Headshot and Photo Colorizer must contain the missing comma; all samples must parse.
4. Merge and deploy this docs PR after step 3. Recheck the guide → reference → quickstart → pricing → API-key path on desktop and at 320px mobile width.
5. After 8–12 weeks, compare settled 28-day developer-query clicks, docs-attributed key creation, and first successful jobs within seven days. Separate new signups from existing-account activation.

The production crawl covers 106 HTML pages plus llms.txt; the page-level Search Console/indexation/quality report remains with the originating task. After deployment, compare settled 28-day relevant developer-query clicks, docs-attributed key creators, and first successful API jobs within seven days. Separate existing-account activation from new signup; the conversion forecast is assumption-based. Revert any individual copy/navigation change if it worsens integration usability.

Before/after evidence was refreshed September 8: live production versus local 40d0f96, desktop at 1280 CSS px and mobile at 320 × 720 CSS px with scrollY 550. The mobile body and document widths are both 320. The subsequent merge of main adds only Models recommendations; captured guide/snippet/navigation files are identical on 61ac003.

Before and after

Live production is shown on the left; the PR result is shown on the right.

Desktop — 1280 CSS px

Before	After

Mobile — 320 × 720 CSS px at scrollY 550

Before	After

The same captures are attached to ENG-4838.

[runshouse]

Next step from PR triage: https://linear.app/magic-hour/issue/ENG-4838 contains the exact remaining evidence/release gates and acceptance checks. This is a documented handoff, not a claim that the remaining verification or publication is complete.

[davidhu2000]

Implementation review looks good. The SDK argument fixes, Python syntax corrections, navigation changes, and API-first titles are coherent, and checks pass.

I am not approving yet because this PR release sequence requires web-app #14762 to be merged and deployed first, followed by production OpenAPI sample verification. #14762 is still open. Please complete that gate and re-request review.