Add support for Cadiro's Gambit

[kylande01]

Fixes #2415 .

Description of the problem being solved:

Cadiro's Gambit was lacking support, only granting the implicit attack speed modifier.
This update adds an item-gated configuration dropdown with "Not selected" as its default. Users can select between the six mutually exclusive arrow types for each arrow type applying its changes across PoB for:

• Crescendo: Arrows chain 6 additional times with 60% increased damage for each chain
• Splinter: Arrows split towards 6 targets
• Reversing: Reversing arrows pierce all targets and return to you
• Diamond: Arrows are critical hits with 60% increased critical damage bonus
• Covetous: Enemies killed with covetous arrows drop items with 600% increased rarity
• Blunt: Blunt arrows cause 600% increased stun buildup

Each selection applies only that arrow's effects, and all effects are scoped to Arrow skills. Reversing Arrow also displays its 100% Return Chance in the Calcs panel, but does not include added DPS calculations to avoid false damage reporting. Dropdown tooltips describe the effect of each arrow as per the affix descriptions from poe2db.

Steps taken to verify a working solution:

• Verified the selector only appears while Cadiro's Gambit is equipped and defaults to “Not selected”.
• Manually verified each dropdown tooltip and the visible effects in the development build.
• Added integration coverage for exclusivity, item removal, all six arrow effects, and non-arrow skill scoping.
• Focused test: 9 successes, 0 failures, 0 errors.
• Full test suite: 575 successes, 0 failures, 0 errors.
• Regenerated ModCache.lua and verified that only the Cadiro's Gambit entry changed.

Link to a build that showcases this PR:

https://pobb.in/wHXUWmsIXjgP
This is a basic build using Shockchain Arrow on a Deadeye just to make sure all arrow interactions are accounted for. All automated integration tests also passed

Before screenshot:

After screenshot:

With six different arrow types I won't flood this page with screenshots. Please feel free to verify further if needed.

I'm a long time user of PoB and a first time contributor. If I've made any sort of error in this request at all, please let me know and I'll fix it immediately. Thank you!