docs: InfluxDB 2 steering docs

[fredjoonpark]

Populates the InfluxDB 2-specific steering docs for the Timestream for InfluxDB Kiro power:

• query-guide.md — Flux and InfluxQL query patterns, aggregations, filtering, and Grafana variable usage
• dashboard-guide.md — Grafana data source config (Flux/InfluxQL), panel examples for time-series, gauges, tables, and alerts
• development-guide.md — bucket management, token scoping, retention policies, DBRP mappings, and task scheduling
• migrations.md — migration paths to/from InfluxDB 2
• troubleshooting.md — v2-specific error resolution for Flux queries, write failures, and token issues