Remove non-actionable guidance from Portuguese (pt-BR) style guide

Description

This MR deletes unmeasurable guidance, editorial planning sections, vague tone descriptors, and non-actionable local references. Adds English source to CTA examples. Keeps only concrete, language-specific translation rules the agent can act on.

Changes Made

Removed:

• Content Types section (Website Pages, Blog Posts, Product Descriptions) - this was more like editorial planning, not translation guidance. The agent translates existing content, it doesn't decide blog structure or information architecture.
• Body Text subsection (paragraph length, sentence counts, "practical examples with clear explanations") , because the agent translates existing paragraphs, not restructures them to meet word counts.
• Headlines subsection (Problem→Solution→Benefits→Action structure, 6-10 word targets) , same reasoning as above
• Business Context subsection ("build trust through expertise," "emphasize teamwork") — vague tonal aspirations the agent can't verify or implement during YAML translation.
• Local References ("Brazilian business context," "cultural references when applicable," "Brazilian constructions and expressions") -- agent translates source content, doesn't inject regional references.
• "Balance Portuguese translations with accepted English terms" is unactionable without criteria. The termbase already makes this decision per-term.
• Links include /pt-br/ prefix -- this is unverified site structure assumption; URL handling ideally belongs in core style guide and system prompt, not per-language.
• Unmeasurable checklist items like "warm professional tone maintained," "active voice predominant" -- same spirit as the percentage metrics from other guides: #21 (comment 3031525869)
• CTA vague descriptors ("use warm, inviting language," "emphasize ease of use," "include collaborative language") , removed and replaced with concrete English -> Portuguese CTA examples.
• Closing aspirational note ("Always prioritize natural Brazilian Portuguese flow and cultural warmth") is redundant with guidance that's already in the document.

Kept: você form rules, proclitic preference, gerund usage, article frequency note, concrete CTA examples with English mapping, and all verifiable checklist items. I am not a language specialist, so these will further need to be verified

No rewording or restructuring beyond deletions desorbed above.

Related

• Related to #21

Type of Change

• New feature
• Bug fix
• Documentation update
• Style guide or terminology update
• Configuration change
• Other (please describe)

Changelog Entry

• Changelog entry added to CHANGELOG.md
• Entry is in the [Unreleased] section
• Used appropriate category (Added/Changed/Fixed/Deprecated/Removed/Security)
• Included MR reference at the end of the entry (e.g., (!123))