Expose query log via Postgres-backed DuckLake view

[bill-ph]

Summary

• expose ducklake.system.query_log as a live DuckLake view over the native Postgres query-log table in DuckLake metadata
• migrate an existing physical ducklake.system.query_log table to ducklake.system.query_log_ducklake_legacy before creating the view
• skip native Postgres setup when the query-log view is already live, and preflight/verify the hidden Postgres source before touching legacy state
• ensure the native Postgres querylog.query_log_entries table and month partitions exist, including repair for rows that landed in the default partition
• emit query-log partition bounds with explicit UTC offsets
• update query-log docs and Postgres compatibility notes

Tests

• go test -count=1 ./server ./server/flightsqlingress
• git diff --check
• just lint

[github-actions]

Test Impact Plan

Deterministic summary of how this PR changes tests, CI runners, and coverage-risk signals.

Summary

Area	Added	Changed	Deleted
Test files	1	2	0
E2E/journey files	0	0	0
Workflow files	0	0	0

Signals

• Test cases: +13 / -0
• Assertions: +95 / -2
• Skips or known failures added: 2
• Workflow continue-on-error added: 0
• Workflow path filters added: 0
• Test commands removed from justfile: 0
• E2E/journey retry lines added: 0

Coverage risk: likely reduced

Warnings

• New skips or known failures (likely reduced)
  • 2 skip/allowlist line(s) added