breakglass UI v2: attachable sessions (tmux model) + mobile-first redesign

Full audit-driven rework. Keeps the proven SSE-translation + verb logic; everything else upgraded for phone-primary use.

Backend — server owns the session, clients attach (Viktor's tmux idea):
- session.py: SessionManager + Session with an event log, subscriber pub/sub, and turns that run DETACHED (keep going if the client disconnects).
- GET /api/session/{id}/stream = attach (SSE): replays the transcript then tails live; per-event id: lines so an EventSource auto-reconnect resumes from Last-Event-ID (free re-attach). POST /{id}/prompt starts a detached turn; POST /{id}/cancel = Stop. Replaces the old one-shot /api/chat.
- agent_session trimmed to the argv + translate_event helpers; 21 new/updated tests (replay, Last-Event-ID resume, broadcast, detached turn, resume, cancel, routes) — 53 green.

Frontend — mobile-first via the frontend-design skill (emergency-console aesthetic):
- EventSource attach (native auto-reconnect, zero client reconnect logic); transcript.js folds events->messages with id-dedupe so replays never double-render (30 unit assertions).
- Installable PWA: manifest + icons (wrench/break-glass mark) + apple-mobile-web-app meta + theme-color; viewport-fit=cover + safe-area; 100dvh; 16px composer (no iOS zoom).
- One-tap diagnosis presets (Triage / Memory-OOM / Disk / Services / QEMU-wedged) mapped to the devvm's real failure modes; Stop button while a turn runs.
- Foldable VM-control sheet, cycle the dominant recovery action w/ confirm, output capped 46vh.
- a11y: fixed --ink-faint contrast 3.6:1 -> 6.1:1 (WCAG AA); >=44px tap targets. Deleted the obsolete fetch-reader sse.js (EventSource replaces it).

Verified: 53 backend tests + 30 transcript assertions; Playwright @390x844 (input on-screen y=721-821, presets/sheet/fold/cap); local integration smoke vs the real backend (attach->caught-up, 404, verbs, PWA served).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/public/icon.svg

@@ -0,0 +1,64 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="512" height="512" viewBox="0 0 512 512" role="img" aria-label="devvm breakglass">
+  <defs>
+    <!-- layered near-black surface, matching the app theme -->
+    <radialGradient id="bg" cx="68%" cy="22%" r="92%">
+      <stop offset="0%" stop-color="#12303a"/>
+      <stop offset="42%" stop-color="#0b0f14"/>
+      <stop offset="100%" stop-color="#06080b"/>
+    </radialGradient>
+    <linearGradient id="steel" x1="0" y1="0" x2="1" y2="1">
+      <stop offset="0%" stop-color="#7df0f3"/>
+      <stop offset="55%" stop-color="#3dd1d6"/>
+      <stop offset="100%" stop-color="#1f6f72"/>
+    </linearGradient>
+    <filter id="glow" x="-40%" y="-40%" width="180%" height="180%">
+      <feGaussianBlur stdDeviation="7" result="b"/>
+      <feMerge><feMergeNode in="b"/><feMergeNode in="SourceGraphic"/></feMerge>
+    </filter>
+  </defs>
+
+  <!-- rounded-square field (safe for maskable: art kept within central ~80%) -->
+  <rect width="512" height="512" rx="112" fill="url(#bg)"/>
+  <rect x="6" y="6" width="500" height="500" rx="108" fill="none" stroke="#1c2530" stroke-width="3"/>
+  <!-- faint scanline texture -->
+  <g opacity="0.05" stroke="#ffffff" stroke-width="2">
+    <line x1="0" y1="148" x2="512" y2="148"/>
+    <line x1="0" y1="220" x2="512" y2="220"/>
+    <line x1="0" y1="292" x2="512" y2="292"/>
+    <line x1="0" y1="364" x2="512" y2="364"/>
+  </g>
+
+  <!-- fracture burst (amber): the "break the glass" radiating cracks -->
+  <g stroke="#f5b657" stroke-width="9" stroke-linecap="round" stroke-linejoin="round"
+     fill="none" opacity="0.92" filter="url(#glow)">
+    <path d="M256 256 L142 132"/>
+    <path d="M256 256 L120 250"/>
+    <path d="M256 256 L150 372"/>
+    <path d="M256 256 L372 380"/>
+    <path d="M256 256 L392 246"/>
+    <path d="M256 256 L360 138"/>
+    <!-- cross-cracks -->
+    <path d="M186 196 L150 250"/>
+    <path d="M210 320 L172 318" opacity="0.7"/>
+    <path d="M326 318 L356 350" opacity="0.7"/>
+  </g>
+
+  <!-- wrench, struck across the burst (cyan steel) -->
+  <g filter="url(#glow)">
+    <path fill="url(#steel)" stroke="#0e3133" stroke-width="6" stroke-linejoin="round"
+      d="M344 150
+         a62 62 0 0 0 -82 76
+         L150 338
+         a26 26 0 0 0 0 37
+         l11 11
+         a26 26 0 0 0 37 0
+         l112 -112
+         a62 62 0 0 0 76 -82
+         l-41 41
+         l-40 -11
+         l-11 -40
+         z"/>
+    <!-- handle highlight -->
+    <path d="M171 350 l128 -128" stroke="#bdf6f8" stroke-width="7" stroke-linecap="round" opacity="0.6"/>
+  </g>
+</svg>

frontend/public/manifest.webmanifest

@@ -0,0 +1,31 @@
+{
+  "name": "devvm breakglass",
+  "short_name": "breakglass",
+  "description": "Emergency recovery console for the devvm — chat with a repair agent or power-cycle the VM directly.",
+  "start_url": "./",
+  "scope": "./",
+  "display": "standalone",
+  "orientation": "portrait",
+  "background_color": "#06080b",
+  "theme_color": "#06080b",
+  "icons": [
+    {
+      "src": "./icon.svg",
+      "type": "image/svg+xml",
+      "sizes": "any",
+      "purpose": "any maskable"
+    },
+    {
+      "src": "./icon-192.png",
+      "type": "image/png",
+      "sizes": "192x192",
+      "purpose": "any maskable"
+    },
+    {
+      "src": "./icon-512.png",
+      "type": "image/png",
+      "sizes": "512x512",
+      "purpose": "any maskable"
+    }
+  ]
+}