COD-107 remote SSH: custom port + advanced connection options (escape hatch)

The Remote case form could only reach port-22, default-identity, directly
SSH-able hosts. Add an escape-hatch set of SSH connection options so Codeman
can reach a host like aa-desktop (custom port 2222, ed25519 identity, cloudflared
SOCKS5 ProxyCommand) the way ssh-aa-desktop does — without shelling out to that
wrapper.

- Model (types/session.ts): new optional RemoteSshOptions (identityFile,
  socksProxy, jumpHost, extraSshOptions) on RemoteHost AND SessionRemote; all
  absent = today's behavior. toSessionRemote() carries them case->session.
- Shared buildSshConnectionArgs(remote) in remote-hosts.ts: pure, exported,
  ordered ssh connection tokens (-o BatchMode=yes, -p, -i <abs identity with
  ~/$HOME expanded + shellescaped>, -J, -o ProxyCommand=nc -X 5 -x <socks>
  %h %p emitted as ONE shellescaped token so %h %p reach ssh literally, then
  each extraSshOptions -o). Both buildRemoteLaunchCommand (tmux-manager.ts) and
  buildRemoteTmuxCheckCommand now use it, so the prereq probe and the real
  launch connect identically. checkRemoteTmuxAvailable widened to accept the
  options (callers already pass the full host).
- Validation (schemas.ts): identityFile (no newline/NUL), socksProxy
  (host:port), jumpHost (no shell metachars), extraSshOptions (KEY=VALUE,
  reject newline/NUL/backtick/$() — defense-in-depth on operator-entered config.
- UI (index.html + session-ui.js): SSH Port field + collapsible "Advanced SSH"
  section (identity, SOCKS proxy, jump host, extra -o options one per line);
  wired into the remote-host create payload.

Empty-options remotes emit byte-identical ssh to before (pinned by test).

Tests: test/remote-ssh-options.test.ts (buildSshConnectionArgs +
buildRemoteLaunchCommand + buildRemoteTmuxCheckCommand for the aa-desktop set,
escaping/%h %p/identity-~ expansion, byte-identical back-compat); case-routes
schema tests (advanced options round-trip; malformed extraSshOptions/socksProxy
rejected). tsc/eslint/frontend-syntax/prettier/build clean.

Acceptance (real remote, no wrapper): the emitted command connected to
aa-desktop through the cloudflared SOCKS proxy and created a durable remote
tmux session (verified independently via ssh-aa-desktop: CONNECTED_NO_WRAPPER,
STILL_ALIVE_AFTER_DETACH); checkRemoteTmuxAvailable over the proxy returned
{ok:true, tmuxPath:/usr/local/bin/tmux}; test session cleaned up.

src/web/public/index.html

@@ -1673,11 +1673,41 @@
               <label>SSH Username</label>
               <input type="text" id="remoteHostUsername" placeholder="ubuntu" autocomplete="off" autocapitalize="off" spellcheck="false">
             </div>
+            <div class="form-row">
+              <label>SSH Port</label>
+              <input type="number" id="remoteHostPort" placeholder="22" min="1" max="65535" autocomplete="off">
+              <span class="form-hint">Optional. Leave blank for the default port 22.</span>
+            </div>
             <div class="form-row">
               <label>Codex Command Override</label>
               <input type="text" id="remoteHostCodexCommand" placeholder="exec codx personal" autocomplete="off" autocapitalize="off" spellcheck="false">
               <span class="form-hint">Optional. Leave blank to use exec codex on the remote host.</span>
             </div>
+            <details class="advanced-options">
+              <summary>Advanced SSH</summary>
+              <div class="advanced-options-content">
+                <div class="form-row">
+                  <label>Identity File</label>
+                  <input type="text" id="remoteHostIdentityFile" placeholder="~/.ssh/remote_ed25519" autocomplete="off" autocapitalize="off" autocorrect="off" spellcheck="false">
+                  <span class="form-hint">Optional. Path to a private key on this machine (passed to ssh -i). Never the key contents.</span>
+                </div>
+                <div class="form-row">
+                  <label>SOCKS Proxy</label>
+                  <input type="text" id="remoteHostSocksProxy" placeholder="127.0.0.1:1080" autocomplete="off" autocapitalize="off" spellcheck="false">
+                  <span class="form-hint">Optional. host:port of a SOCKS5 proxy (e.g. cloudflared). Routes ssh through it via a ProxyCommand.</span>
+                </div>
+                <div class="form-row">
+                  <label>Jump Host</label>
+                  <input type="text" id="remoteHostJumpHost" placeholder="bastion@10.0.0.1:22" autocomplete="off" autocapitalize="off" spellcheck="false">
+                  <span class="form-hint">Optional. [user@]host[:port] for ssh -J (jump/bastion host).</span>
+                </div>
+                <div class="form-row">
+                  <label>Extra -o Options</label>
+                  <textarea id="remoteHostExtraSshOptions" rows="3" placeholder="StrictHostKeyChecking=accept-new&#10;ConnectTimeout=10" autocomplete="off" autocapitalize="off" spellcheck="false"></textarea>
+                  <span class="form-hint">Optional. One KEY=VALUE per line; each becomes an ssh -o option.</span>
+                </div>
+              </div>
+            </details>
           </div>
           <!-- Manage Tab -->
           <div class="modal-tab-content hidden" id="case-manage">