ci: temporarily make release builds and publishing manual

[VibeSWE]

PRs currently run the full release-target build matrix, main-branch pushes publish edge images, tag pushes launch release builds, and frontend CI uploads a distributable archive automatically. Temporarily require manual runs for these builds and outputs.

• Change the multi-platform build matrix, release pipeline, and all three edge-image publishing workflows to workflow_dispatch only.
• Keep frontend checks automatic on pushes and PRs, but package and upload the frontend release archive only on manual runs. Browser failure reports remain available.
• Add a required existing release-tag input to the release pipeline. All release checkouts, GitHub release uploads, and versioned Docker tags use that input, so dispatching from main still builds and publishes the selected tag.
• Lint, coverage, and integration-test workflows retain their existing triggers.

After merging into main, use Actions → select a workflow → Run workflow. For the release pipeline, enter an existing tag such as v3.2.5. The equivalent CLI invocation is:

gh workflow run release.yml --repo VibeEngineeringAI/parseable --ref main -f tag=v3.2.5

Validation:

• Parsed all workflow YAML files.
• Verified manual-only triggers, all seven release checkouts and uploads, Docker version tags, and frontend packaging conditions.
• Actionlint v1.7.12: no new findings; the six existing action-runtime findings match origin/main (shellcheck and pyflakes disabled because shell and Python scripts were unchanged).
• git diff --check passed.

This is a separate PR against main, independent of the CLA fix in #6.

---

^{Need help on this PR? Tag @codesmith-bot with what you need. Autofix is disabled.}