docs: fix malformed Rd syntax in @param k description

[LeonidasZhak]

Summary

Fix double backtick in sum_run's @param k roxygen comment that produces broken \verb{} output in sum_run.Rd and mean_run.Rd.

Before:

@param k (`integer`` vector or single value)

Renders as: \verb{integer`` vector or single value)...} — malformed Rd.

After:

@param k (`integer` vector or single value)

Renders as: \code{integer} vector or single value — correct Rd.

Problem

In src/runner.cpp line 783, the roxygen comment for @param k had a double backtick instead of a single backtick. This caused roxygen2 to generate broken \verb{} Rd markup in sum_run.Rd and mean_run.Rd (which inherits from sum_run via @inheritParams).

Validation

• tools::checkRd('man/sum_run.Rd') — passes
• tools::checkRd('man/mean_run.Rd') — passes
• All 1043 tinytest tests pass (tinytest::test_package('runner') — All ok)
• 1 source file changed (src/runner.cpp), 3 Rd files regenerated

Files Changed

File	Change
src/runner.cpp	1 char fix: -> `` in@param k`
R/RcppExports.R	Auto-regenerated
man/sum_run.Rd	Auto-regenerated
man/mean_run.Rd	Auto-regenerated
man/runner.Rd	Cross-ref normalization

Duplicate Check

• PR docs: fix roxygen typos in fill_run, sum_run, max_run, which_run #109 fixes fill_run defaults, sum_run @return, max_run/which_run descriptions — does NOT touch @param k
• PR docs: fix na_rm param description inherited by all *_run functions #112 fixes na_rm param description — does NOT touch @param k
• No duplicate work found

[gogonzo]

Thanks!

[LeonidasZhak]

Withdrawing this small automated PR while I consolidate an oversized batch of contributions and reduce maintainer review burden. Sorry for the noise, and thank you for maintaining the project.