#237 Make Browser Infrastructure first-class in docs

Change

• make Browser Infrastructure a first-class product across SDK READMEs, Cloud docs, navigation, and agent-facing llms artifacts
• keep V2, V3, and V4 references available while removing stale lifecycle, pricing, and unsupported capability claims
• repair runnable x402, n8n, and chat-UI examples and preserve renamed deep-link anchors
• make llms generation complete, deterministic, locked, and rollback-safe; enforce drift in CI

Why

Search and agent retrieval treated Browser Infrastructure as an implementation detail and repeated mutable or contradictory product claims. This PR gives SDK users one exact taxonomy and durable canonical links.

Proof

• strict Mintlify validation: PASS
• generated llms artifacts: two runs byte-identical
• docs/nav denominator: 97/97 pages represented exactly once
• V2/V3/V4 OpenAPI sources present in compact and full machine surfaces
• generator concurrency, bootstrap, signal rollback, and stale-lock recovery checks: PASS
• git diff/check and shell syntax: PASS
• fresh Codex review: CLEAN
• fresh Claude Code Opus review: CLEAN

Risk / rollback

Docs, generated text, and CI only; no SDK runtime or OpenAPI behavior changes. Old version routes and compatibility anchors remain. Roll back by reverting commit 97dac0e.

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Summary by cubic

Makes Browser Infrastructure a first-class product across SDK READMEs, Cloud docs, navigation, and agent-facing llms.txt artifacts, and drops stale lifecycle, pricing, and unsupported capability claims. Docs and CI only, so no SDK runtime or OpenAPI behavior changes; V2, V3, and V4 routes stay available.

Documentation updates

• Renames the Agent and Browser product groups to Browser Use Agents and Browser Infrastructure throughout navigation and page copy.
• Replaces duplicated token and per-step pricing tables with links to browser-use.com/pricing.
• Removes unsupported claims like "bypass any CAPTCHA" and free-credit offers.
• Fixes runnable x402, n8n, and chat-UI examples; n8n now authenticates with X-Browser-Use-API-Key instead of Authorization: Bearer and polls using the run id.
• Preserves renamed deep-link anchors so existing URLs keep working.
• Removes stale v3 announcement, Playwright, and open-source development/roadmap pages; CDP usage stays covered in the Browser Infrastructure quickstart.

Generated artifacts and CI

• docs/generate-llms-txt.sh now produces all six llms.txt / llms-full.txt artifacts under a kernel lock with staged, atomic, rollback-safe publishing.
• Adds a docs:llms task and docs-generated CI workflow that fails when tracked artifacts drift or navigation misses a page.