[Misc] Add data for theoretical Valentine's event

[Fontbane]

What are the changes the user will see?

• Feel the love in the Valentines Event!
  • Lasts from February 14, 2025, to February 21, 2025, midnight UTC
  • Enjoy 2x Shiny boost in all modes, as well as a boosted candy friendship multiplier in Classic mode, from 3x to 4x!
  • Foster togetherness with the DNA Splicers, found very rarely in Great Tier in Classic mode for this event! And don't worry about candy friendship- candy friendship gained by fusions will go from 1/2 the usual amount to 2/3 for this event!
  • Find special species as lovely surprises in the Uncommon Breed, Berries Abound, and Fight or Flight events!
    • Pokemon encountered this way also have an extra chance to be shiny!
    • The species included are:
      • The Nidoran family
      • Igglybuff, Jigglypuff, and Wigglytuff
      • Smoochum and Jynx
      • Volbeat and Illumise
      • Roselia and Roserade
      • Luvdisc
      • Woobat and Swoobat
      • Frillish and Jellicent
      • Alomomola
      • Furfrou with a Heart Trim
      • Espurr and Meowstic
      • Spritzee and Aromatisse
      • Swirlix and Slurpuff
      • Milcery and Alcremie
      • Indeedee
      • Tandemaus and Maushold
      • Enamorus in its Incarnate Forme

Why am I making these changes?

• Would like to have this event for community engagement. Not guaranteed to happen.

What are the changes from a developer perspective?

• Adds the boostFusions boolean to TimedEvent interface, as well as areFusionsBoosted function. If true, DNA Splicers are set to great tier with weight of 1 (in non spliced modes) and candy friendship gained by each constituent starter is divided by 1.5 rather than 2.
• Adds functionality for event encounters to have a specified form index
• Adds PLACEHOLDER banner graphics which will need to be replaced once they're finalized

Screenshots/Videos

Title screen with placeholder banner

DNA splicers in Great tier

Event encounter with heart trim Furfrou

How to test the changes?

Set the date for the event to the current date

Checklist

• I'm using beta as my base branch
• There is no overlap with another PR?
• The PR is self-contained and cannot be split into smaller PRs?
• Have I provided a clear explanation of the changes?
• Have I tested the changes manually?
• Are all unit tests still passing? (npm run test)
  • Have I created new automated tests (npm run create-test) or updated existing tests related to the PR's changes?
• Have I provided screenshots/videos of the changes (if applicable)?
  • Have I made sure that any UI change works for both UI themes (default and legacy)?

Are there any localization additions or changes? If so:

• Has a locales PR been created on the locales repo?
  • If so, please leave a link to it here:
• Has the translation team been contacted for proofreading/translation? YES, BANNERS NEED TO BE FINALIZED TOO