Sample high-volume analytics events

[jahooma]

Summary

• Add deterministic sampling for high-volume analytics while preserving core lifecycle and error events.
• Summarize CLI log and tool-use payloads to avoid sending raw params or contents by default.
• Add full-telemetry env overrides for targeted debugging and document them.

Validation

• bun test common/src/util/tests/analytics-sampling.test.ts packages/agent-runtime/src/tests/xml-tool-result-ordering.test.ts
• bun test cli/src/utils/tests/analytics-client.test.ts
• bun run --filter @codebuff/common typecheck
• bun run --filter @codebuff/agent-runtime typecheck
• bun run --filter @codebuff/sdk typecheck
• bun run --filter @codebuff/cli typecheck
• git diff --check