docs(app-platform): sync the platform docs with the shipped code

- app-manifest-spec.md: full rewrite from the real schema in
  core/container/src/manifest.rs — it was 5 months stale and missing the
  entire modern feature set (build, network/network_aliases, derived_env,
  secret_env, generated_secrets/certs, data_uid, files, interfaces, hooks,
  extensions flatten) and documented wrong network_policy values.
- app-developer-guide.md: add generated_secrets/generated_certs/
  network_aliases/hooks to the field table.
- APP-PACKAGING-MIGRATION-PLAN.md: phase status stamped (1-3 done, 5 mostly,
  4+6 open); deleted meshtastic app removed from regression-proof lists.
- registry-manifest-design.md: status design → implemented (phases 1-3),
  stale manifest_dir:Option line fixed.
- marketplace-protocol.md: reframed proposal → as-built (marketplace.rs +
  RPCs + UI shipped; create-invoice noted; schema disambiguated).
- manifest-hooks-design.md: phase 3 (indeedhub) done, phase 4 resolved via
  orchestrator+generated_secrets instead of hooks.
- README/architecture: restore the NIP-07 signer-bridge claim — it is real
  (neode-ui/public/nostr-provider.js), the earlier audit only grepped Rust.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

README.md

@@ -43,7 +43,7 @@ Storage (FileBrowser, Immich, Nextcloud), Productivity (Vaultwarden), Media (Jel
 - Ed25519 node identity with DID Documents (did:key)
 - Multi-identity management (Personal/Business/Anonymous)
 - W3C Verifiable Credentials issuance and verification
-- Nostr integration: NIP-33 node discovery, NIP-44/NIP-04 encryption, relay hosting
+- Nostr integration: NIP-33 node discovery, NIP-44/NIP-04 encryption, NIP-07 signer bridge for iframe apps, relay hosting
 - Decentralized Web Node (DWN) record sync between federated nodes over Tor
 
 ### Multi-Node Federation