fix: list new queries in the PR comment, not just count them

[veksen]

Follow-up to the run-page / baseline work (Query-Doctor/Site bug report; epic Query-Doctor/Site#3106).

Problem

The PR comment header shows e.g. "74 queries analyzed | 1 new query" and the roll-up says "1 new", but the body never lists which query is new. A new query only appeared in the comment if it carried an index recommendation (under "This PR introduces queries with recommendations"). A new query with no recommendation — e.g. an index-covered query that's new but not a problem — was counted in the tally and listed nowhere, making "1 new" unactionable from the PR.

Fix (analyzer-only)

compareRuns already produces newQueries with full SQL — the data was there, just never rendered. buildViewModel now also returns displayNewQueries: the new queries whose hash carries no index recommendation (the ones that do have a recommendation already render under the recommendations section, so they're excluded here to avoid double-listing). The template gains a "This PR introduces new queries" section listing each one's SQL preview, cost, and run link (cost N · no index suggestion).

No API change needed: the analyzer already computes the comparison locally whenever it can fetch a baseline. (When no baseline is available there's nothing to attribute — the existing no-baseline / temporarily-unavailable messaging covers that.)

Tests

• buildViewModel: a new query without a recommendation is listed in displayNewQueries; a new query with a recommendation is not double-listed.
• Template: renders the "This PR introduces new queries" section with the query's SQL and cost N · no index suggestion.
• 54/54 affected unit tests pass; tsc --noEmit clean. Two golden-file snapshots gained a single blank line — the same empty-section gap every other optional section already emits (GitHub collapses it); verified the snapshot delta is whitespace-only.

[github-actions]

Query Doctor Analysis

3 queries analyzed

0 regressed · 0 improved · 0 new · 0 removed

2 pre-existing issues

• SELECT "guests"."id", "guests"."session_id", "guests"."username", "guests"."avatar_path", "guests"."color", "guests"."side", "guests"."audio_recording_path", "guests"."audio_recording_public", "gue...
  index assets(event_id, inserted_at desc)
  cost 31,003,449 → 1,498 (100% reduction)
• SELECT * FROM guest_ip_addresses WHERE ip_address = '127.0.0.1';
  index guest_ip_addresses(ip_address)
  cost 154,402 → 8 (100% reduction)

_{Using assumed statistics (10000000 rows/table). For better results, sync production stats.}

_{More detail → get_ci_run({ runId: "019ed20f-b573-7262-b2aa-3b74da5f9085" }) · view run · docs}