docs: add a grouped documentation index; fix references to now-local-only docs

Two concrete, verifiable documentation gaps from the open-source review:

- docs/ had no index. Adds docs/README.md grouping the 60-odd published docs by
  task — getting started, architecture, app development, design docs, ADRs,
  security, roadmap — in the bitcoin/bitcoin doc/ style the plan called for.
  Every link in it resolves (checked). The top-level README now points at it as
  the front door rather than duplicating the list.

- ROADMAP.md and tests/lifecycle/TESTING.md linked docs/multinode-testing-plan.md,
  which moved to local-only (it is a fleet node inventory, not published). Those
  references now describe the scope split in prose instead of pointing at a file
  that is not in the public tree.

The index is honest about what is missing: it names the three app-developer
docs the plan flagged as gaps (quadlet compilation, container lifecycle,
secrets materialisation) as not-yet-written, and points at the authoritative
code for each rather than pretending they exist.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/README.md

@@ -0,0 +1,78 @@
+# Archipelago documentation
+
+Start here. This index groups the docs by what you're trying to do. The
+authoritative behaviour is always the code in `core/`; where a doc and the code
+disagree, the code wins and the doc is a bug.
+
+## Getting started
+
+- [User Walkthrough](user-walkthrough.md) — setting up and using a node, from hardware to daily use
+- [Talking to your node](COMMANDS.md) — the conversational command surface
+- [Seed Verification](SEED-VERIFICATION.md) — independently verify your 24-word backup
+- [Troubleshooting](troubleshooting.md) — common problems and how to resolve them
+- [Gamepad / Controller Navigation](GAMEPAD-NAV.md) — driving the UI from a controller
+
+## Architecture
+
+- [Architecture](architecture.md) — the system at a glance
+- [Multi-Node Architecture](multi-node-architecture.md) — how nodes relate across a fleet
+- [API Reference](api-reference.md) — the JSON-RPC surface
+
+## App development
+
+- [App Developer Guide](app-developer-guide.md) — build and package a containerized app
+- [App Manifest Specification](app-manifest-spec.md) — the manifest schema, field by field
+- [Registry-Distributed Manifests](registry-manifest-design.md) — how manifests reach nodes via the signed catalog
+- [Decentralized Marketplace Protocol](marketplace-protocol.md) — publishing apps via an external registry
+- [Bitcoin RPC Relay](bitcoin-rpc-relay.md) — letting an external wallet reach the node's Bitcoin RPC
+- [Companion Pairing QR](companion-pairing-qr.md) — the pairing handoff contract
+- [TV input inside iframe apps](tv-input-iframe-apps.md) — keyboard/gamepad routing into embedded apps
+
+> **Known gap (tracked):** three app-developer references named in the
+> open-source plan are not yet written — how a manifest compiles to a
+> Quadlet/systemd unit, the container-lifecycle reconciler state machine, and
+> the `generated_secrets` materialisation flow. Until they land, the source of
+> truth is the code: `core/archipelago/src/container/quadlet*.rs`,
+> `prod_orchestrator.rs`, and `container::secrets` respectively.
+
+## Design docs
+
+These record why a thing is built the way it is. They are design records, not
+step-by-step guides, and some predate the current implementation.
+
+- [Registry-Distributed Manifests](registry-manifest-design.md)
+- [DHT Distribution](dht-distribution-design.md)
+- [Bitcoin Multi-Version](bitcoin-multi-version-design.md)
+- [Dual Ecash](dual-ecash-design.md)
+- [Hardware Signer](hardware-signer-design.md)
+- [Manifest Hooks](manifest-hooks-design.md)
+- [Meshroller Integration](meshroller-integration-design.md)
+- [Nostr Git Source Hosting](nostr-git-source-hosting.md)
+- [Nostr Identity Import](nostr-identity-import-plan.md) · [Nostr Signer Login (research)](nostr-signer-login-research.md)
+- [Streaming Ecash (phase 4)](phase4-streaming-ecash-plan.md)
+- [App Packaging Migration](APP-PACKAGING-MIGRATION-PLAN.md)
+
+## Decisions (ADRs)
+
+- [ADR-001: Podman over Docker](adr/001-podman-over-docker.md)
+- [ADR-002: DID Key Method for Node Identity](adr/002-did-key-method.md)
+- [ADR-003: Nostr Relays for Discovery](adr/003-nostr-for-discovery.md)
+- [ADR-004: Tor Hidden Services for Peer Communication](adr/004-tor-for-peer-communication.md)
+- [ADR-005: ChaCha20-Poly1305 for Backup Encryption](adr/005-chacha20-backup-encryption.md)
+- [ADR-006: Nostr Relays for Marketplace Discovery](adr/006-nostr-marketplace-discovery.md)
+- [ADR-007: DID-Based Federation Trust](adr/007-did-federation-trust.md)
+- [ADR-008: Dual Key Strategy (Ed25519 + Secp256k1)](adr/008-dual-key-strategy.md)
+- [ADR-009: Manifest-Level Container Security](adr/009-manifest-container-security.md)
+- [ADR-011: DWN Deprioritization](adr/011-dwn-deprioritization.md)
+
+## Security
+
+- [Security Policy](../SECURITY.md) — how to report a vulnerability
+- [PSBT Signing Architecture](security/PSBT-SIGNING-ARCHITECTURE.md)
+- [Bitcoin RPC Proxy Exposure](security/BITCOIN-RPC-PROXY-EXPOSURE.md)
+- [Entropy Enforcement (KEY-05)](security/KEY-05-ENTROPY-ENFORCEMENT.md)
+
+## Roadmap & history
+
+- [Roadmap](ROADMAP.md) — where the project is going
+- [archive/](archive/README.md) — superseded design and status documents, kept for provenance

docs/ROADMAP.md

@@ -49,9 +49,8 @@ security-first.
 ## 🔄 In progress
 
 - **Multinode pass** — run the same production gate across the whole test
-  fleet, plus cross-node federation/mesh suites
-  ([`multinode-testing-plan.md`](multinode-testing-plan.md)). This is the
-  current exit criterion.
+  fleet, plus cross-node federation/mesh suites. This is the current exit
+  criterion.
 - **Quadlet default flip** — flip the validated Quadlet path from opt-in to
   default fleet-wide; eliminates the last container-flapping root cause.
 - **Container-flapping elimination** — reconciler churn and failed-unit