Add missing manifest icons and PoC documentation

- Add emoji icon field to hello-dashboard, icd-test-runner,
  sdk-test-runner, and team-activity-log manifests
- Create README.md for tasks and schedules packages marking them
  as Proof of Concept with documented graduation criteria

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/tasks/README.md

@@ -0,0 +1,22 @@
+# Tasks
+
+**Status: Proof of Concept**
+
+Task management surface rebuilt as a Starlark extension. Ships with core
+for SDK validation purposes, not as a permanent commitment.
+
+## Purpose
+
+Validates all three trigger primitives (event bus, webhook, cron) and
+proves the full extension surface stack: Starlark API routes, ext_data
+tables, SDK UI components, and notifications.
+
+## Graduation Criteria
+
+To become a permanent core package, tasks must meet:
+
+1. **Feature completeness** — assignees, comments, attachments, subtasks
+2. **Test coverage** — API contract tests in the ICD test runner
+3. **Performance** — tested at 1000+ tasks with acceptable load times
+4. **Design review** — UI/UX matches platform design language
+5. **No kernel special-casing** — runs purely through extension APIs