chore: release 2025.8.4

[mise-en-dev]

🚀 Features

• (tasks) breaking Add environment variable directives for mise tasks by @jdx in #5638

[github-actions]

Hyperfine Performance

mise x -- echo

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
mise-2025.8.3 x -- echo	18.8 ± 0.5	18.2	24.1	1.05 ± 0.03
mise x -- echo	17.8 ± 0.3	17.4	21.6	1.00

mise env

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
mise-2025.8.3 env	18.1 ± 0.2	17.6	19.1	1.05 ± 0.02
mise env	17.2 ± 0.2	16.7	19.2	1.00

mise hook-env

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
mise-2025.8.3 hook-env	17.8 ± 0.3	17.4	20.3	1.06 ± 0.02
mise hook-env	16.9 ± 0.2	16.4	17.8	1.00

mise ls

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
mise-2025.8.3 ls	15.6 ± 0.2	15.2	16.7	1.00
mise ls	15.7 ± 0.2	15.2	16.4	1.01 ± 0.02

xtasks/test/perf

Command	mise-2025.8.3	mise	Variance
install (cached)	189ms	✅ 125ms	+51%
ls (cached)	80ms	78ms	+2%
bin-paths (cached)	64ms	63ms	+1%
task-ls (cached)	493ms	460ms	+7%

✅ Performance improvement: install cached is 51%