fix: give the common-skill buttons their own label and tagline

The seven selector buttons were rendering `kind` and `use`, which belong
to the detail panel. ponytail's button read "SIMPLIFICATION INSTINCT" and
a full paragraph of prose where today's page reads "SIMPLIFY" and
"minimum code that holds". English was wrong, not just Portuguese
missing, on all seven.

Those two lines are not in `interactiveCopy`, which is why task 05b had
nothing to migrate them from: the English lives in the
`full-guide/index.html` markup and the Portuguese in `translations.pt`.
Adds `label` and `tagline` to the `commonSkills` schema and to all seven
entries, both taken verbatim from those two sources, and points the
buttons at them. The panel keeps reading `kind` and `use`.

This closes the last 13 of the 102 `translations.pt` entries. Coverage in
`dist/full-guide/index.html` is now 102 of 102.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/content/commonSkills/research.json

@@ -16,5 +16,7 @@
     "en": "Practitioner articles add context; they do not override official behavior.",
     "pt": "Artigos de praticantes dão contexto; não substituem comportamento oficial."
   },
-  "source": "https://github.com/mattpocock/skills/blob/6654f6b60cd9d5be8b54c6fafe44346dabeb3b76/skills/engineering/research/SKILL.md"
+  "source": "https://github.com/mattpocock/skills/blob/6654f6b60cd9d5be8b54c6fafe44346dabeb3b76/skills/engineering/research/SKILL.md",
+  "label": { "en": "INVESTIGATE", "pt": "INVESTIGAR" },
+  "tagline": { "en": "primary sources first", "pt": "fontes primárias primeiro" }
 }