feat(polling-contracts): add generic polling interface with TypeScript types and Zod schemas

- Add @timesafari/polling-contracts package with comprehensive type definitions
- Implement GenericPollingRequest, PollingResult, and PollingScheduleConfig interfaces
- Add Zod schemas for StarredProjectsRequest/Response and DeepLinkParams validation
- Include calculateBackoffDelay utility with unified retry policy (exponential, linear, fixed)
- Add OutboxPressureManager for storage pressure controls and back-pressure signals
- Implement TelemetryManager with cardinality budgets and PII redaction
- Add ClockSyncManager for JWT timestamp validation and skew tolerance
- Include comprehensive unit tests with Jest snapshots and race condition testing
- Add JWT_ID_PATTERN regex for canonical JWT ID format validation
- Support idempotency with X-Idempotency-Key enforcement
- Implement watermark CAS (Compare-and-Swap) for race condition prevention

This establishes the foundation for the new generic polling system where host apps
define request/response schemas and the plugin provides robust polling logic.

packages/polling-contracts/package.json

@@ -0,0 +1,29 @@
+{
+  "name": "@timesafari/polling-contracts",
+  "version": "1.0.0",
+  "description": "TypeScript contracts and Zod schemas for TimeSafari polling system",
+  "main": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "scripts": {
+    "build": "tsc",
+    "test": "jest",
+    "test:snapshots": "jest --updateSnapshot",
+    "lint": "eslint src --ext .ts",
+    "lint-fix": "eslint src --ext .ts --fix"
+  },
+  "dependencies": {
+    "zod": "^3.22.4"
+  },
+  "devDependencies": {
+    "@types/jest": "^29.5.5",
+    "@typescript-eslint/eslint-plugin": "^5.57.0",
+    "@typescript-eslint/parser": "^5.57.0",
+    "eslint": "^8.37.0",
+    "jest": "^29.7.0",
+    "ts-jest": "^29.1.0",
+    "typescript": "^5.2.2"
+  },
+  "files": [
+    "dist/**/*"
+  ]
+}