docs: add Spanish translations for all skills and project docs

[juanitourquiza]

Summary

This PR adds complete Spanish translations for the entire agent-skills repository, following the same pattern as PR #120 (Chinese translations).

What was translated

• 21 skills → skills/{name}/skill-es.md
  • api-and-interface-design, browser-testing-with-devtools, ci-cd-and-automation, code-review-and-quality, code-simplification, context-engineering, debugging-and-error-recovery, deprecation-and-migration, documentation-and-adrs, frontend-ui-engineering, git-workflow-and-versioning, idea-refine, incremental-implementation, performance-optimization, planning-and-task-breakdown, security-and-hardening, shipping-and-launch, source-driven-development, spec-driven-development, test-driven-development, using-agent-skills
• 4 root docs → -es.md
  • README-es.md
  • AGENTS-es.md
  • CLAUDE-es.md
  • CONTRIBUTING-es.md
    Total: 25 new translated files

Translation conventions

• Technical terms preserved in English: pull request, debugging, CI/CD, API, feature flags, commit, branch, merge, DORA, Hyrum's Law, Chesterton's Fence, etc.
• Code blocks, commands, file paths, and ASCII diagrams left exactly as in the originals.
• Markdown formatting (headings, tables, lists, checkboxes, frontmatter) fully preserved.
• Professional tone oriented to senior software engineers.

Scope alignment with PR #120

This PR mirrors the scope and structure of the Chinese translation PR (#120) to maintain consistency across language contributions.

Files changed: 25 new files, 0 modifications to existing files.

[incrediblemohnish5]

Multilingual Integration is always good

[incrediblemohnish5]

So can all languages in the world be translated through AI first and if there are any errors then community volunteers can help to make the AI generated content errors free and truly global

[juanitourquiza]

So can all languages in the world be translated through AI first and if there are any errors then community volunteers can help to make the AI generated content errors free and truly global

It's possible, but I think is better choice for someone, for example, Chinese, French, Italian, Russian for the test. What do you think about this option?

[incrediblemohnish5]

yeah you are right

[federicobartoli]

Translation work is substantial and I appreciate the effort, but there are structural issues that need addressing before this can land:

1. Translations won't be discovered by agent tooling. The skill-es.md files keep the same name: frontmatter as the English originals (name: test-driven-development). Agent harnesses that load skills by name will hit a conflict between SKILL.md and skill-es.md. And the filename itself isn't a discovery target — Claude Code, Cursor, and others look for SKILL.md, not language variants. Same applies to README-es.md, AGENTS-es.md, CLAUDE-es.md. Net effect: 6500+ lines that no agent will actually load — only humans who manually navigate to them.

2. No sync mechanism = guaranteed drift. Every English skill update requires a Spanish update. Without CI to detect divergence (or a clear policy that translations will lag), the Spanish docs will be stale within months and silently misleading.

3. Use case isn't clear. If these are human reference docs, they should be marked as such ("translation reference, may lag the English source") and probably moved under translations/es/ rather than living next to canonical files. If they're meant to be agent-loadable, the architecture needs work (language-suffixed names, a registry, or multi-lang frontmatter).

4. This is a translation-policy call, not a code change. Same point I raised on docs: add Chinese (zh-CN) README translation #144 — adopting multi-language docs is a commitment. The repo currently has no infrastructure for it (no drift CI, no glossary, no governance for who reviews translation accuracy). Worth a maintainer decision before merging this and docs: add Chinese translations for all skills and project docs #120.

Suggest holding both PRs and opening an issue first to settle the policy. If the answer is "yes, translations are wanted," the PRs can come back with the architectural fixes (proper discovery, drift detection).