feat(runtime): cmd:screenshot + cmd:force-incident + prismarine-viewer dep

Three live-verification surfaces on top of v0.1.0:

1. cmd:screenshot { reason?, frames? } → runtime/viewer.takeScreenshot
   - Headless POV render via prismarine-viewer.headless to
     state/<host>/screenshots/<ISO>-<reason>.mp4 (1 frame ≈ ~10 KB).
   - Lazy-loads the heavy GL stack on first call so the bot doesn't pay
     the cost on startup or in TUI-only sessions.
   - Returns { ok, path, error } over IPC LOG event.
   - Known limitation: needs node-canvas. node-canvas v3 (current npm
     default) is incompatible with prismarine-viewer's API; v2 doesn't
     build under Node 24 (node-pre-gyp fail). So today the feature is
     wired and the IPC contract is stable, but the underlying render
     fails fast with "createCanvas is not a function". A future cleanup
     can either fork the renderer or pin a Node 20 toolchain.

2. cmd:force-incident { kind?, reason? } → filePostCritique path
   - Operator-triggered demo of the critic → proposal → auto-improve →
     auto-patch chain. Was previously only observable when the bot
     genuinely got stuck. Now a single IPC call exercises the full
     loop on demand.
   - Verified live 2026-05-26: critic call returned a real, useful
     critique ("attack zombie returns done while target is alive →
     blocks gather.logs"), proposal landed with all sections including
     the Critic block, auto-improve picked it up within 10 s.

3. prismarine-viewer + canvas added to dependencies so npm install
   builds the deps once and the IPC surface is always available.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

package.json

@@ -19,6 +19,7 @@
     "test": "node --test runtime/skills/contract.test.js runtime/skills/groups.test.js runtime/skills/compat.test.js runtime/skills/recovery-tunnel-out.test.js runtime/curriculum.test.js runtime/social/social.test.js runtime/social/conversation.test.js runtime/stuck-incident.test.js runtime/compat.test.js runtime/reflex.test.js runtime/base-site.test.js runtime/locations.test.js runtime/watch-filter.test.js runtime/world-journal.test.js runtime/scenario-memory.test.js runtime/critic.test.js runtime/skill-library.test.js runtime/modes.test.js scripts/edit-scope.test.js scripts/lint-patch.test.js"
   },
   "dependencies": {
+    "canvas": "^3.2.3",
     "dotenv": "^16.4.5",
     "ink": "^7.0.4",
     "ink-text-input": "^6.0.0",
@@ -31,6 +32,7 @@
     "mineflayer-pvp": "^1.3.2",
     "mineflayer-tool": "^1.2.0",
     "prismarine-item": "^1.18.0",
+    "prismarine-viewer": "^1.33.0",
     "react": "^19.2.6",
     "vec3": "^0.2.0"
   },