fix(ci): set required environment variables for npm publishing

[jdx]

Summary

• Fixed the failing npm publishing step in the release workflow
• Added required environment variables MISE_VERSION and RELEASE_DIR that the release-npm.sh script depends on

Problem

The npm publishing step was failing in CI because the release-npm.sh script requires MISE_VERSION and RELEASE_DIR environment variables to be set. These variables were previously set in the release.sh script which runs in an earlier workflow step, but environment variables don't persist across GitHub Actions workflow steps.

Solution

Explicitly export these required variables in the npm publishing step:

• MISE_VERSION - obtained from scripts/get-version.sh
• RELEASE_DIR - set to "releases" (the directory where release artifacts are stored)

Test plan

• The next release should successfully publish npm packages without errors
• Verify npm packages are published to registry after merge and next release

Fixes: https://github.com/jdx/mise/actions/runs/17495121479/job/49696552525

🤖 Generated with Claude Code

[Copilot]

Pull Request Overview

This PR fixes a failing npm publishing step in the CI release workflow by adding required environment variables that the npm release script depends on. The issue was that environment variables from earlier workflow steps don't persist across GitHub Actions steps.

• Adds explicit export of MISE_VERSION and RELEASE_DIR environment variables
• Uses scripts/get-version.sh to obtain the current version
• Sets the release directory to "releases" where artifacts are stored

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[github-actions]

Hyperfine Performance

mise x -- echo

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
mise-2025.9.1 x -- echo	18.6 ± 0.5	18.0	22.6	1.00
mise x -- echo	18.6 ± 0.3	18.1	21.2	1.00 ± 0.03

mise env

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
mise-2025.9.1 env	17.9 ± 0.3	17.4	19.1	1.00
mise env	18.0 ± 0.3	17.4	19.9	1.00 ± 0.02

mise hook-env

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
mise-2025.9.1 hook-env	17.8 ± 0.4	17.2	20.8	1.00
mise hook-env	17.8 ± 0.3	17.2	19.1	1.00 ± 0.03

mise ls

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
mise-2025.9.1 ls	16.0 ± 0.2	15.5	16.9	1.00
mise ls	16.0 ± 0.2	15.6	17.5	1.00 ± 0.02

xtasks/test/perf

Command	mise-2025.9.1	mise	Variance
install (cached)	164ms	✅ 102ms	+60%
ls (cached)	61ms	61ms	+0%
bin-paths (cached)	66ms	65ms	+1%
task-ls (cached)	466ms	482ms	-3%

✅ Performance improvement: install cached is 60%