feat(format): add core:columns-rows formatter for HQL table output

[vinaysrini]

Summary

• Add a reusable core:columns-rows text formatter and ExpandColumnsRows helpers for the standard {columns, rows} query result shape
• Route --format table|csv|tsv|markdown|jsonl through FormatArrayOutput when execute/get payloads match that shape
• Wire execute hql:run to use the new formatter so tabular output works out of the box

Test plan

• go test ./pkg/format/ ./pkg/registry/
• go build -o bin/harness ./cmd/harness/
• ./bin/harness execute hql:run --query 'find entity "platform:project" | select {name} | limit 5' --format table
• Same query with default format (text → table) and --format csv
• Confirm non-columns/rows execute commands still reject --format table

Made with Cursor

[CLAassistant]

All committers have signed the CLA.

[vinaysrini]

Addressed all review findings in 0e914a7:

1. Duplicate column name collisions — dedup now tracks every generated ID (used) and advances a per-base suffix until unique. Covered by x, x_2, x → x, x_2, x_3.
2. --raw + tabular formats — reject early with the standard --raw is only supported with --format json (same as list path). Tests: RawTableRejected, RawJSONKeepsEnvelope.
3. Empty result (columns: []) — still recognized as columns/rows shape; table renders empty and exits 0. Covered by TestExpandColumnsRows_EmptyResult.
4. Dispatch / --raw test coverage — added tests for item_expr extraction into table output, raw rejection, and raw JSON envelope preservation.
5. Truncation notice consistency — (truncated) now also appears for --format table / markdown via PageMeta.Notice (human-readable only; csv/tsv/jsonl stay clean). Covered by TruncatedTableNotice.