feat: add typed template registry

[rogerchappel]

Summary

• Add a typed template registry for next-app, oss-cli, and python-api.
• Make stackforge templates render from the registry instead of inline literals.
• Validate template metadata/order and CLI output with a deterministic registry check.

Verification

• Tests or checks run: pnpm check
• Tests or checks run: pnpm check:templates
• Manual smoke: node dist/index.js templates
• Manual smoke: node dist/index.js init oss-cli demo --dry-run

Risk Level

• Low
• Medium
• High

Notes: CLI output now includes name and category fields from the registry, alongside existing keys/descriptions.

Rollback Plan

• Revert the two commits on this branch to restore inline template literals and remove the registry check.

Human Decision Needed

• None
• Maintainer review
• Product/design decision
• Security/privacy review
• Other:

[rogerchappel]

CrewCmd links

• Implementation task: TSK-71
• Sentinel review task: TSK-72

Status

• PR is ready for review.
• Verification passed: pnpm check, pnpm check:templates, node dist/index.js templates, node dist/index.js init oss-cli demo --dry-run.
• No blockers.