- Replace trivial same-word matching pairs (Bag->Bag, Menu->Menu, etc.)
with actual Tagalog vocabulary (Payong->Umbrella, Pagkain->Food, etc.)
- Fix misleading "Match opposite adjectives" prompt to accurately describe
the Tagalog-to-English matching exercise
- Remove awkward slash-separated alternative in directions fill-in-the-blank

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

The phrases lesson had "___ ko." with blank "Hindi ko alam" which
would produce the nonsensical "Hindi ko alam ko." Fixed to
"Hindi ko ___." with blank "alam" for correct "Hindi ko alam."

Also changed let to const for seenSections Set (mutated via .add(),
not reassigned).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Introduce sections concept (Section 1-4 planned) with section banners
on the home page. Expand Section 1 (Foundations) from 6 to 30 topics
covering CEFR A1 material: greetings, basics, introductions, courtesy,
numbers, colors, family, emotions, adjectives, body parts, clothing,
animals, home, nature, time, days, weather, verbs, daily routine, food,
shopping, market, restaurant, school, jobs, sports, health, directions,
travel, and common phrases.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>