chore(deps): pin opencode CLI + SDK to v1.4.9 (#1471)

* chore(deps): pin opencode CLI and SDK to v1.4.9

- Bump constants.json opencodeVersion v1.2.27 -> v1.4.9 (CI source of
  truth consumed by ci-tests, build-desktop, alpha/prerelease/release
  workflows, and opencode-agents).
- Bump @opencode-ai/sdk across app, story-book, orchestrator,
  opencode-router, server-v2, and refresh the lockfile so all workspaces
  resolve to 1.4.9.

* refactor(app): adapt to @opencode-ai/sdk 1.4.9 type changes

- Move Model.reasoning reads to Model.capabilities.reasoning in
  model-config.ts and model-behavior.ts (SDK flattened capabilities).
- Simplify utils/providers.ts to a pass-through; Provider now carries
  source/options and Model.cost reshapes to {input, output, cache,
  experimentalOver200K}, which the mapper no longer needs to translate.
- Cast session.todo() result to TodoItem[] (SDK Todo has no id).
- Update server-v2 test fixtures from 1.2.27 to 1.4.9.

apps/opencode-router/package.json

@@ -44,7 +44,7 @@
     "test:npx": "bun scripts/test-npx.mjs"
   },
   "dependencies": {
-    "@opencode-ai/sdk": "^1.1.31",
+    "@opencode-ai/sdk": "^1.4.9",
     "@slack/socket-mode": "^2.0.5",
     "@slack/web-api": "^7.13.0",
     "commander": "^12.1.0",