Fix oldest stading record

[campos20]

After thewca/worldcubeassociation.org#13304, tables that we were using to compute oldest standing records are now empty. This PR introduces a way to compute oldest standing records without using ranks_single and ranks_average, only using results.

[Copilot]

Pull request overview

Updates the “Oldest standing records” statistics queries to compute current WR/CR/NR ages directly from the results table (instead of relying on ranks_single / ranks_average), restoring functionality after the ranks tables became empty.

Changes:

• Rewrites the World/Continental/National record queries using CTEs + row_number() over results joined with competitions.
• Adds/updates a sqlQueryCustom variant intended to compute per-person (WCA ID) results for this statistic.
• Adjusts selected competition fields used for link formatting (e.g., using c.name).

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[Copilot]

In sqlQueryCustom, the 'Average' branch selects best as the record value even though it ranks by average and is labeled as 'Average'. This will display the wrong value for average personal bests; select average as the record value in that branch.

Suggested change

	best record,
	average record,

[Copilot]

In the 'Average' branch of the WR CTE, the query selects best as the record value even though it filters on regional_average_record = 'WR'. This will display the single result instead of the average for current average WRs; use the average column as the record value for this branch.

Suggested change

	best record,
	average record,

[Copilot]

In the 'Average' branch of the continental records CTE, the query selects best as the record value while filtering on regional_average_record. This will format/display the single result under the 'Average' type; use average as the record value in this branch.

Suggested change

	best record,
	average record,

[Copilot]

In the 'Average' branch of the national records CTE, the query selects best as the record value while filtering on regional_average_record = 'NR'. This will show the single result in the 'Average' row; use the average column as the record value for this branch.

Suggested change

	best record,
	average record,

[Copilot]

The national records query now outputs region as r.country_id (country code/id) instead of the country name (previously countries.name). If the UI expects a human-readable region label in this column, join countries and select the name here to avoid regressing the output format.