docs: reposition to verifiable web retrieval for AI agents - #6

Summary

Repositions UnSearch from "open-source Tavily alternative, 10× cheaper" to verifiable web retrieval for AI agents — every result signed, hashed, snapshotted, and replayable months later. Driven by Q1–Q2 2026 market shifts that made the prior wedge unsellable to indie devs (Anthropic native web_search, Codex CLI first-party search, MCP search vendor saturation, Tavily→Nebius, Brave free-tier kill, Exa price hike) and three regulatory/litigation forces that opened a sharper wedge for regulated AI (Q1 2026 $145K US court sanctions for hallucinated legal citations, Harvey AI 1-in-6 hallucination rate at $8B valuation, EU AI Act Article 12 enforcement August 2026).

What changed (30 files, +2241 / -1859)

• Strategy docs rewritten (11): docs/strategy/{positioning,icp,jtbd,value-prop,market,user-journey,pricing,gtm,sales-playbook,mrr-plan,README}.md. New personas: Priya (ICP-1, regulated-AI startup eng lead), David (ICP-2, regulated-company AI platform director), Anika (ICP-3, citation-integrity research/newsroom). Maya (indie dev) retired — eaten by native LLM search.
• Top-level rewrites (5): README.md, docs/README.md, docs/roadmap.md, docs/introduction.mdx, apps/web/app/page.tsx landing (new ProblemStrip with $145K / 1-in-6 / 40-60% / Aug 2026 stats; MCP-install hero; new pricing tiers including $24K self-host v1).
• New ADRs (5): 0009-verifiable-retrieval-as-product-surface, 0010-cloudflare-containers-as-origin-runtime, 0011-wacz-aligned-signed-envelope, 0012-mcp-first-distribution, 0013-icp-shift-to-regulated-ai. ADR-0003 (Tavily-compat) downgraded to compatibility surface.
• New spec: docs/citation-envelope.md — wire format (HMAC v1, WACZ-Auth-aligned, PKI v2 path).
• Feature matrix rewritten around verifiable retrieval; comparison columns now include Anthropic native web_search, Codex CLI search, Webrecorder.
• Migration housekeeping: docs/migration/from-tavily.md keeps as compatibility surface with a banner; SDK package name fixed (@unsearch/sdk, class UnSearch). docs/mint.json dropped 20+ dead navigation references (features/*, api-reference/auth/*, etc.) and added new docs + ADRs.
• Stale cleanup:
  • firecrawl/ — orphaned git submodule (no .gitmodules), empty in worktree, git rm --cached.
  • docs/getting-started/next-steps.md — referenced /root/unsearch/... paths and wrong Stripe pricing ($29/10K vs actual $19/25K).
  • quickstart.sh banner — "Tavily Alternative" → "Verifiable Retrieval for AI Agents".

What this PR does NOT change

• Backend code, API endpoints, Workers, container deploy config — those are Week 1–3 work per the approved rebuild plan at ~/.claude/plans/app-unsearch-dev-is-not-deployed-luminous-wilkinson.md.
• nginx/, monitoring/, ecosystem.config.js, scripts/setup-stripe.*, docs/architecture.md, docs/cloudflare-architecture.md, docs/ai-pipeline.md — all still load-bearing for self-host / operations.
• A repo-structure audit (app/ vs apps/backend/ duplication, monitoring/ vs apps/backend/monitoring/, etc.) is the next session — see follow-up.

Test plan

• Skim README.md and apps/web/app/page.tsx for tone consistency.
• Verify ADR cross-references resolve (0009 ↔ 0010 ↔ 0011 ↔ 0012 ↔ 0013).
• Confirm docs/strategy/README.md reading order links land on the right files.
• pnpm --filter @unsearch/web build succeeds on the new landing copy.
• docs/mint.json validates against the Mintlify schema.
• GitHub repo description still reads as the verifiability-first line (set in an earlier session).