chore: prepare the template for public release

[DeyangChan]

Prepares vstack-template-base for publication as an open-source GitHub template.

License and community docs

• MIT LICENSE, copyright Cavalry Collective (verified against the GitHub org, the README, and the maintainer domain).
• CONTRIBUTING.md, SECURITY.md, Contributor Covenant 2.1 CODE_OF_CONDUCT.md, .github/CODEOWNERS.
• README now states audience, status, support route, and license, and no longer claims an instantiated project is production-ready before its CI, infrastructure, secrets, and deployment are configured and verified.

Workflows no longer report false greens

• .github/workflows/ci.yml (every check commented out, job ended in echo "TODO...") and deploy.yml (printed a TODO and exited 0) are gone from the executable path.
• New template-integrity.yml checks only what this repository actually contains: whitespace invariants, relative-link resolution, the stack-pack contract from stacks/README.md, the add-on contract, and a guard against muted or placeholder workflow steps. permissions: contents: read.
• The generic application scaffolds moved to .github/workflows/examples/{ci,deploy}.yml.example, which Actions does not execute. Day-1 step 7 says when to copy each, and deploy stays uncopied until a target exists.

Stack corrections against current vendor docs

• vercel-csr — rewritten around Vercel's zero-config Fastify support: a detected entrypoint calling listen() on the environment's port. Removes the app.server.emit("request", req, res) forwarding, the app.ready() adapter, the "never call listen()" rule, and the @vercel/node handler plus catch-all rewrite.
• wechat — was internally inconsistent: it prescribed Node 20 (EOL 24 Mar 2026) on a managed runtime that does not offer it, with Fastify 4 (EOL 30 Jun 2025). Now an SCF Web Function deployed as a container image on Node 24 LTS (Active LTS, EOL Apr 2028) with Fastify 5, started by the container command on port 9000. The managed runtime survives as a labelled Legacy managed runtime note that names Node 18 / Fastify 4 as end-of-life and not recommended.
• wechat database — "MySQL 8" becomes TDSQL-C (CynosDB) MySQL 8.0, the newest engine that product offers; TDSQL-C is wire-compatible with 5.7 and 8.0 only, so MySQL 8.4 LTS is not available here. Local and CI pin to the same 8.0 line.

Small fixes

• .claude/scheduled_tasks.lock added to .gitignore (local generated state, never tracked).
• Escaped the ampersands in the design guide's Google Fonts URL.

Test plan

• template-integrity.yml's Python step, extracted verbatim from the YAML, reports 0 problem(s) on this tree.
• The same step reports 2 errors and exits 1 against a probe file with a broken relative link and trailing whitespace, so the check is not vacuous.
• The workflow-honesty step runs clean under bash over .github/workflows/*.yml.
• git diff --check clean.
• All three workflow YAML files parse.
• Confirmed the only unescaped & left in design-guide.html are inside a <style> and a <script> block, where escaping would be wrong.