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, 26 insertions, 2 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/i18n.js b/packages/meshbay-hub/src/meshbay_hub/static/i18n.js
index 3450735..f0c5cef 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/i18n.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/i18n.js
@@ -38,7 +38,7 @@ const en = {
   'register.title': 'Register',
   'register.username': 'Username',
   'register.email': 'Email',
-  'register.password': 'Password (min 8 chars)',
+  'register.password': 'Passphrase (min 12 chars)',
   'register.confirm': 'Confirm password',
   'register.submit': 'Register',
   'register.loading': 'Creating account...',
@@ -48,7 +48,11 @@ const en = {
   'register.success_msg': 'You can now log in with your credentials.',
   'register.go_login': 'Go to login',
   'register.err_mismatch': 'Passwords do not match',
-  'register.err_min_len': 'Password must be at least 8 characters',
+  'register.err_min_len': 'Use at least {n} characters',
+  'register.err_too_weak': 'Too easy to guess. Your passphrase is what protects '
+    + 'your keys where they are stored — a few unrelated words work well.',
+  'register.strength': 'Strength: about {bits} bits. This protects the copy of '
+    + 'your keys kept on the nodes you join, so it is worth getting right.',
 
   // Home
   'home.welcome': 'Welcome to MeshBay',
@@ -120,6 +124,10 @@ const en = {
   'settings.coming_soon': 'Coming soon.',
   'settings.profile': 'Profile',
   'settings.username': 'Username',
+  'settings.node_pins': 'Node identities',
+  'settings.node_pins_hint': "Each node's identity key is remembered the first time you connect. If it changes, the connection is refused — that is expected only when an operator reinstalls a node. Verify with them before clearing.",
+  'settings.node_pins_count': '{n} pinned',
+  'settings.node_pins_clear': 'Clear pinned identities',
   'settings.appearance': 'Appearance',
   'settings.theme': 'Theme',
   'settings.theme_light': 'Light',
@@ -236,6 +244,22 @@ const en = {
   'members.invite_title': 'Invite member',
   'members.username_placeholder': 'Username',
   'members.invite_btn': 'Invite',
+  'members.pair_title': 'Pair this browser with your node',
+  'members.pair_hint': 'Your node only accepts operator actions — invites, file '
+    + 'deletion — from a browser it has been paired with. Run '
+    + '`meshbay-node operator pair` on the node and type the code here. The code '
+    + 'never passes through the hub, which is what stops the hub from claiming to '
+    + 'be you.',
+  'members.pair_btn': 'Pair',
+  'members.pair_success': 'This browser is now paired with the node.',
+  'members.invite_code_ready': 'Invitation code for {user} — send it to them the way '
+    + 'you normally talk. It works once, and it never passes through the hub.',
+  'members.invite_code_hint': 'They enter it the first time they open this group. '
+    + 'You do not need to be online then.',
+  'group.join_code_title': 'This node needs to recognise you',
+  'group.join_code_hint': 'Ask whoever invited you for the one-time code, and enter '
+    + 'it here. After that this browser is recognised and you will not be asked again.',
+  'group.join_code_btn': 'Join',
 
   'notif.title': 'Notifications',
   'notif.empty': 'No notifications',