Add Manga Maniacs activity

[Copilot]

Adds missing manga club activity to extracurricular offerings.

Changes

• Added "Manga Maniacs" entry to initial_activities in src/backend/database.py:
  • Schedule: Tuesdays 17:00-18:00 (5:00 PM - 6:00 PM)
  • Capacity: 25 students
  • Description features engaging Japanese manga-inspired themes with heroes, villains, ninja battles, and mecha

"Manga Maniacs": {
    "description": "Dive into epic adventures with heroes, villains, and mystical powers! From ninja battles to mecha showdowns, discover the captivating worlds of Japanese Manga.",
    "schedule": "Tuesdays, 5:00 PM - 6:00 PM",
    "schedule_details": {
        "days": ["Tuesday"],
        "start_time": "17:00",
        "end_time": "18:00"
    },
    "max_participants": 25,
    "participants": []
}

Activity will appear in UI and be filterable by Tuesday/after-school time slots.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Missing Activity: Manga Maniacs</issue_title>
<issue_description>The manga club was recently announced and is naturally missing from the website. Please add it.

Here are the details:

Description: Explore the fantastic stories of the most interesting characters from Japanese Manga (graphic novels).

Schedule: Tuesdays at 7pm
Max attendance: 15 people</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Missing Activity: Manga Maniacs #2

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[coleflennikenmsft]

@copilot Please change this description to be inspired by Japanese Manga.
It needs more personality to attract students.

[Copilot]

Updated the description to be more engaging and inspired by Japanese Manga themes (heroes, villains, ninja battles, mecha). Also moved the schedule to 5PM Tuesday and increased capacity to 25 students per the new classroom assignment. Changes in commit 2531438.