fix(rules): show GATILHO in Portuguese, and diff the PT half too

The skill detail panel's label read TRIGGER in both languages. The copy
data carries the Portuguese in `skillTriggerLabelPt`, but the island asks
for `skillTriggerLabel`, which is "TRIGGER" under both locales -- so the
translated value was never reachable. Legacy renders it inline:
`language === 'pt' ? 'GATILHO' : 'TRIGGER'`.

Fixed by putting the Portuguese where the lookup goes, `pt.skillTriggerLabel`,
and dropping the unreachable `skillTriggerLabelPt` from both locales. Nothing
else reads that key.

rendered-text-diff.mjs grows a `--pt` flag and now reports both directions.
English parity was hiding this: a page can paint every English string and
still leave a block untranslated, because the Portuguese half is a separate
set of nodes, and a string the Astro page renders but the legacy page does
not is equally wrong -- it means a translation was invented or an English
string was left where the legacy page swaps it.

/rules/ is now 119 of 119 in both languages, zero either way.

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

src/content/rules/copy.json

@@ -56,7 +56,6 @@
     "skillReadSkill": "READ SKILL ↗",
     "skillReadSkillPt": "LER SKILL ↗",
     "skillTriggerLabel": "TRIGGER",
-    "skillTriggerLabelPt": "GATILHO",
     "copyStatus": "Prompt copied.",
     "copyStatusPt": "Prompt copiado.",
     "copyFallback": "Select the text manually.",
@@ -118,8 +117,7 @@
     "stageOpenSourcePt": "ABRIR FONTE ↗",
     "skillReadSkill": "LER SKILL ↗",
     "skillReadSkillPt": "LER SKILL ↗",
-    "skillTriggerLabel": "TRIGGER",
-    "skillTriggerLabelPt": "GATILHO",
+    "skillTriggerLabel": "GATILHO",
     "copyStatus": "Prompt copied.",
     "copyStatusPt": "Prompt copiado.",
     "copyFallback": "Select the text manually.",