Release v19.0.0

[flyingrobots]

Summary

• publish the Runtime/Lane/Intent/Observer/Reading/Receipt v19 boundary
• require the one-shot retained-v18 substrate migration
• record the exact merged-main performance and bounded-memory witness

Related: #758

Verification

• npm run release:prep
• merged-main performance run: https://github.com/git-stunts/git-warp/actions/runs/30251600921

[coderabbitai]

📝 Walkthrough

Walkthrough

The PR updates v19 architecture and release messaging, documents the Runtime/Lane API model and migration guidance, revises benchmark notes, and bumps root and package versions to 19.0.0.

Changes

v19 release posture

Layer / File(s)	Summary
Public API and architecture narrative ARCHITECTURE.md, CHANGELOG.md, README.md, docs/topics/README.md	Documentation and release notes now describe the v19 Runtime, Lane, Intent, Observation, Reading, and Receipt model, migration guidance, benchmark details, and observation optimization notes.
Package release versioning jsr.json, package.json, packages/*/package.json	Root and package manifest versions are updated from 18.2.1 to 19.0.0.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Poem

A rabbit hops through v19’s lane,
Runtime opens, receipts remain.
Intent goes in, readings flow,
Benchmarks sparkle, versions grow.
Documentation follows the trail—
Thump-thump-thump, a tidy release tale!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely states the main change: releasing v19.0.0.
Description check	✅ Passed	The description includes summary bullets, an issue reference, and verification; only the ADR checklist is left unfilled.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

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[github-actions]

Release Preflight

• package version: 19.0.0
• prerelease: false
• npm dist-tag on release: latest
• npm pack dry-run: passed
• jsr publish dry-run: passed

If this PR is from a release/* branch and merges to main, Main Push Release Branch Check will run final preflight and create v19.0.0. A maintainer who is a JSR @git-stunts scope member must then dispatch the Release workflow manually.