BOT: Fix #793: separate doc pages for S3 methods with different args

[nikosbosse]

Summary

• Gives three S3 methods their own documentation pages instead of sharing @rdname with their generics, resolving the confusing mixed-argument problem described in How should we document methods that have different arguments than the default method?  #793
• Methods affected: as_forecast_quantile.forecast_sample, as_forecast_point.forecast_quantile, get_pit_histogram.forecast_sample
• Added regression tests verifying method parameter signatures remain distinct

Root cause

When S3 methods have different parameters from their generic (e.g., probs/type vs quantile_level), sharing @rdname lumps all args into one flat list, making it unclear which arguments belong to which method.

What the fix does

Replaces @rdname <generic> with standalone @title/@description/@param blocks on the three affected methods, so each gets its own .Rd page with only its relevant parameters. Cross-links via @seealso connect them back to the generic.

Test coverage added

• as_forecast_quantile.forecast_sample() accepts probs and type args
• as_forecast_point.forecast_quantile() extracts median without extra args
• get_pit_histogram.forecast_sample() accepts integers and n_replicates args
• get_pit_histogram.forecast_quantile() does not accept integers arg
• Formals differ between as_forecast_quantile methods

Closes #793

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.83%. Comparing base (ac0c01a) to head (0ea0f7d).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1087   +/-   ##
=======================================
  Coverage   97.83%   97.83%           
=======================================
  Files          35       35           
  Lines        1845     1845           
=======================================
  Hits         1805     1805           
  Misses         40       40           

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[nikosbosse]

CLAUDE: Automated review — APPROVE. Clean, well-scoped documentation change. Correctly separates three S3 methods (as_forecast_quantile.forecast_sample, as_forecast_point.forecast_quantile, get_pit_histogram.forecast_sample) into their own .Rd pages with proper roxygen blocks, cross-links, and inherited params. The @inheritParams fix in helper-quantile-interval-range.R is necessary and correct. Regression tests cover all specified scenarios. Bonus typo fix (empircal → empirical). No issues found.