feat(credential-sharing): end-to-end-encrypted team credential sharing

Adds a `team` credential provider + team/member management so teammates can
share secrets by email instead of passing .env files over chat. Fully E2E:
the server only ever stores ciphertext, per-member sealed vault keys, and
public keys — it never sees a plaintext value or the vault DEK.

Plugin (@logicsrc/plugin-credential-sharing)
- crypto.ts: X25519 identity keys, per-vault DEK (secretbox), DEK sealed to
  each member's pubkey (crypto_box_seal), value encrypt/decrypt (libsodium)
- identity.ts: local ~/.logicsrc/identity.json (0600) holding the device key
  + API token; never uploads the secret key
- client.ts: typed /api/credshare client
- providers/team.ts: `team:<slug>/<vault>` CredentialProvider (inspect,
  readValues=decrypt, write=encrypt, rollback); fingerprints match env so
  env<->team diffs line up
- fixes latent libsodium-wrappers ESM load bug (createRequire) here + in
  github-secrets

Server (commandboard-api /api/credshare)
- zero-knowledge router: email-code auth, keys, teams, members, invites,
  vaults, sealed grants, ciphertext secrets, audit; membership authz in app
- CredShareStore abstraction: in-memory (dev/tests) + Supabase (prod)
- Resend email transport for login codes + invites (no-op -> echoes locally)
- supabase migration: credshare_* tables, deny-by-default RLS

CLI
- real `logicsrc login` (email code -> token + key upload)
- `logicsrc teams create/list/invite/accept/members/vaults/grant/push/pull`

Web (logicsrc.com/teams + /teams/accept)
- management surface only (browser holds no private key, never decrypts):
  login, view teams/members/vaults, invite, accept

Tests: crypto round-trip, server contract (invite->accept->push->grant->pull
+ authz boundaries), and a real HTTP+client+crypto E2E asserting the server
never holds plaintext. Full workspace build + tests green.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/logicsrc-web/src/app/teams/accept/page.tsx

@@ -0,0 +1,25 @@
+import type { ReactNode } from "react";
+import type { Metadata } from "next";
+import { SiteShell } from "@/components/site-shell";
+import { TeamsClient } from "@/components/teams-client";
+
+export const metadata: Metadata = {
+  title: "Accept invite · LogicSRC Teams",
+  description: "Accept a LogicSRC credential-sharing team invite.",
+  robots: { index: false },
+};
+
+// Invite emails link here as /teams/accept?token=… — log in, then the token is
+// auto-accepted by the client.
+export default async function AcceptInvitePage({
+  searchParams,
+}: {
+  searchParams: Promise<{ token?: string }>;
+}): Promise<ReactNode> {
+  const { token } = await searchParams;
+  return (
+    <SiteShell active="Credentials">
+      <TeamsClient initialToken={token} />
+    </SiteShell>
+  );
+}