fix(ui): align message motion and composer button radius with DESIGN.md; tolerate unreadable staging revision state

- Message entry: 300/420ms power3.out -> Standard 180ms cubic-bezier(.22,1,.36,1) (DESIGN.md section 6); update the layout contract test to the shipped values.
- Composer icon button: full radius instead of 8px (DESIGN.md section 5 Button).
- Staging deploy workflow: fall back to container SHA discovery when .state/deployed-revision exists but is unreadable by the deploy user (Gitea pipeline writes it as root).

frontend/src/app/globals.css

@@ -708,7 +708,7 @@ button:disabled { cursor: default; opacity: .45; }
 .composer { width: min(760px, 100%); display: flex; align-items: flex-end; gap: 10px; margin: 0 auto; border: 1px solid var(--color-border); transition: border-color 140ms ease-out; min-height: 60px; padding: var(--space-2) var(--space-2) var(--space-2) var(--space-4); border-color: var(--color-border-strong); border-radius: var(--radius-lg); background: var(--color-canvas); box-shadow: 0 0 0 1px color-mix(in srgb, var(--color-border) 42%, transparent); }
 .composer:focus-within { border-color: var(--color-action); box-shadow: 0 0 0 3px color-mix(in srgb, var(--color-action) 15%, transparent); }
 .composer textarea { min-width: 0; min-height: 44px; max-height: 128px; flex: 1; resize: none; padding: 11px 0 8px; border: 0; outline: 0; background: transparent; color: var(--color-ink); line-height: 1.5; font-size: 16px; }
-.composer button { width: 44px; height: 44px; display: grid; flex: 0 0 auto; place-items: center; border: 0; color: var(--color-on-dark); cursor: pointer; transition: background-color 120ms ease-out, transform 120ms ease-out; border-radius: var(--radius-md); background: var(--color-action); }
+.composer button { width: 44px; height: 44px; display: grid; flex: 0 0 auto; place-items: center; border: 0; color: var(--color-on-dark); cursor: pointer; transition: background-color 120ms ease-out, transform 120ms ease-out; border-radius: 999px; background: var(--color-action); }
 .composer .composer-stop { background: var(--color-action); }
 .composer .composer-stop:not(:disabled):hover { background: var(--color-action-hover); }
 .composer-footer { width: min(760px, 100%); min-height: 44px; display: flex; align-items: center; margin: var(--space-1) auto 0; }

frontend/src/components/chat-message-row.tsx

@@ -50,8 +50,8 @@ export function ChatMessageRow({
       }, {
         autoAlpha: 1,
         clearProps: "opacity,transform,visibility",
-        duration: message.role === "user" ? 0.3 : 0.42,
-        ease: "power3.out",
+        duration: 0.18,
+        ease: "cubic-bezier(.22, 1, .36, 1)",
         y: 0,
       });
     });