Permission dock offers 'always' even when the request has no always patterns

Title:
Permission dock offers 'always' even when the request has no always patterns

Description:
The permission dock in the session composer renders a button for each of the three
response values once, always, reject. The server-side reply path in
packages/opencode/src/permission/index.ts already treats the always case as a
no-op when the incoming Permission.Info has an empty always pattern list (it
falls through to "once" or rejects), so the client offering a button that the
server will silently downgrade is misleading.

Tracked:

• The client-side permissionRequest() returns a Permission.Info whose always
  field may be empty.
• The current decide(response) path does not check whether the request supports
  always; it just sends reply: "always" to the server.
• On the server, the reply === "always" branch is only meaningful when
  request.always is a non-empty list of patterns to persist.

Expected behaviour:

• When request.always is empty, the client should not offer the always button
  (or, defensively, the decide path should refuse to send "always"), so the
  user never sees a "remember this choice" affordance that has no effect.

Actual behaviour:

• The dock shows the always button for any permission request, regardless of
  whether the request carries always patterns.
• Tapping it sends reply: "always" to the server, which silently falls through
  to a one-off reply.

Plugins: n/a
OpenCode version: dev (10765ff2a9)

Steps to reproduce:

1. Trigger a permission request whose Permission.Info.always is empty (most
   default tool/permission paths, e.g. a plain bash request without an
   explicit pattern list).
2. The permission dock renders three buttons, including "always".
3. Tap "always".
4. The server replies with the same behaviour as "once"; no pattern is
   remembered.

Expected behaviour:

• The "always" button is hidden or disabled when request.always is empty.
• Tapping it (if still rendered) is a no-op, not a silently-downgraded reply.

Operating System: n/a
Terminal: n/a

Related / duplicate check: no related upstream issue found.