merge: Phase 11.5 security remediation, invite redesign, per-node identity

Brings in the security remediation branch. Three bodies of work, and what they
changed about what this project may claim.

Phase 11.5 closed the gap between the documents and the code: the unauthenticated
node HTTP API and the TCP transport deleted, one handshake shared by the
remaining two transports, mutual authentication, structured admin transcripts,
upload confinement, group isolation, revocation that reaches nodes. Six critical
and seven high findings closed, bounded, or deferred by decision.

The invite redesign closed H3 and M3 — the last open High. The hub was the key
directory: an inviter fetched the invitee's key from it and wrapped the group key
for whatever came back, so a hub answering with its own key was handed the group
key by an honest member following the protocol exactly. That lookup is gone. The
node holds the group key and wraps it itself, for a key its recipient proves
possession of, bound to an account by a one-time code the hub never sees. M3 fell
out of the same work: node authority comes from a local roster, never from the
hub.

Per-node identity cut what remains of C4 down to one operator. A single keypair
used to be copied to every node its owner joined; each node now gets its own, so
cracking the bundle on one machine yields a key that is a stranger everywhere
else — and on that machine, one that unlocks nothing its holder did not already
serve. The bundle KDF moved to Argon2id 128 MB, and the hub stopped storing or
publishing user keys at all.

What this project may now say: the hub cannot read your content unless it ships
you malicious client code. T3 remains, accepted (D1), and is what the native
client removes. C4 is reduced, not closed, until 13.3. Chat is still plaintext at
rest until Phase 15. Draft-v5 §2 states each claim against the adversary it holds
against, which is the convention this branch exists to keep.

Four defects were found by deploying it and using a browser, none by the test
suite: a node going deaf on its hub socket, a token that predated group
membership, a client reading values before they were assigned, and identity keys
a browser held but never re-read. The lessons are recorded in CLAUDE.md.

Tests: 343 across the three packages, plus QE/deploy/e2e.py — register, pair,
invite, join, download, stream, second browser, revoke — run against the live
deployment on a wiped hub and node.

1 files changed, 8 insertions, 28 deletions

diff --git a/packages/meshbay-node/src/meshbay_node/transport/tls_cert.py b/packages/meshbay-node/src/meshbay_node/transport/tls_cert.py
index 1354ac9..374fd08 100644
--- a/packages/meshbay-node/src/meshbay_node/transport/tls_cert.py
+++ b/packages/meshbay-node/src/meshbay_node/transport/tls_cert.py
@@ -1,17 +1,18 @@
 """
-Self-signed TLS certificate generation for the node.
+Self-signed TLS certificate generation for the node's QUIC listener.
 
 The cert is used for transport confidentiality only.
 Node identity is verified via Ed25519 PK (from hub), not TLS cert chain.
-Clients connect with ssl.CERT_NONE + verify Ed25519 at the MNP handshake layer.
 
-Certificate is generated once and cached at ~/.config/meshbay/node_tls.pem/.key.
+Phase 11.5 note: the certificate hash is also the intended channel-binding anchor for
+the QUIC handshake proof (11.5.6), since QUIC has no DTLS fingerprint to bind to.
+
+Certificate is generated once and cached at ~/.config/meshbay/node_tls.crt/.key.
 """
 
 import logging
 import os
 from pathlib import Path
-import ssl
 import datetime
 import ipaddress
 
@@ -69,27 +70,6 @@ def generate_self_signed_cert(
     return cert_path, key_path
 
 
-def server_ssl_context(
-    cert_path: Path = DEFAULT_CERT,
-    key_path: Path = DEFAULT_KEY,
-) -> ssl.SSLContext:
-    """SSL context for the node's TCP server."""
-    if not cert_path.exists() or not key_path.exists():
-        generate_self_signed_cert(cert_path, key_path)
-
-    ctx = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
-    ctx.load_cert_chain(certfile=cert_path, keyfile=key_path)
-    ctx.minimum_version = ssl.TLSVersion.TLSv1_3
-    return ctx
-
-
-def client_ssl_context() -> ssl.SSLContext:
-    """
-    SSL context for clients connecting to a node.
-    CERT_NONE because we verify node identity via Ed25519 PK at the MNP layer.
-    """
-    ctx = ssl.SSLContext(ssl.PROTOCOL_TLS_CLIENT)
-    ctx.check_hostname = False
-    ctx.verify_mode    = ssl.CERT_NONE
-    ctx.minimum_version = ssl.TLSVersion.TLSv1_3
-    return ctx
+# `server_ssl_context()` / `client_ssl_context()` were removed in Phase 11.5 along with
+# the TCP+TLS transport they served. QUIC builds its own QuicConfiguration and calls
+# generate_self_signed_cert() directly.