chore(release): sync stable release pipeline to main

[crup]

Syncs the release pipeline and package metadata from next into main before any stable release is run.

Included from next:

• Multi-stage stable release workflow: release guard, source verification, npm latest publish, and GitHub release creation.
• Stable release remains manual and locked to main with confirm_stable_release=publish-stable.
• First stable version guidance defaults to 0.0.1.
• Package SEO metadata: homepage, repository, bugs URL, and expanded npm keywords.
• Release channel docs and README release policy link.

Stable release recommendation:

• First stable should be 0.0.1 because the project already published 0.0.1-alpha.x prereleases.

No npm release should be run until this PR is merged into main and the Release workflow is manually executed from main.

[github-actions]

Bundle size report

Entry	Files	Raw	Gzip	Brotli	Raw delta	Gzip delta	Brotli delta
core	2	4.44 kB	1.52 kB	1.40 kB	0 B	0 B	0 B
timer group add-on	3	10.93 kB	3.83 kB	3.50 kB	0 B	0 B	0 B
schedules add-on	3	8.62 kB	3.02 kB	2.78 kB	0 B	0 B	0 B
duration helper	1	318 B	224 B	192 B	0 B	0 B	0 B
diagnostics helper	1	105 B	115 B	90 B	0 B	0 B	0 B
core CJS	1	4.71 kB	1.63 kB	1.50 kB	0 B	0 B	0 B
timer group CJS	1	11.02 kB	3.86 kB	3.54 kB	0 B	0 B	0 B
schedules CJS	1	8.71 kB	3.04 kB	2.81 kB	0 B	0 B	0 B
duration CJS	1	808 B	475 B	424 B	0 B	0 B	0 B
diagnostics CJS	1	605 B	367 B	326 B	0 B	0 B	0 B