docs: InfluxDB 3 steering docs

[fredjoonpark]

Populates the InfluxDB 3-specific steering docs for the Timestream for InfluxDB Kiro power:

• query-guide.md — SQL and InfluxQL query patterns, DATE_BIN aggregations, Last Value Cache usage, and Grafana variables
• dashboard-guide.md — Grafana data source config (SQL/InfluxQL), panel examples using SQL and InfluxQL
• development-guide.md — database/table management, token scoping, schema-on-write behavior, and processing engine
• migrations.md — migration paths from InfluxDB 2 to 3