MWPW-204225: Support per-OSI promo codes for soft bundle placeholders

[Andrei4226]

Resolves https://jira.corp.adobe.com/browse/MWPW-204225
QA Checklist: https://wiki.corp.adobe.com/display/adobedotcom/M@S+Engineering+QA+Use+Cases

Adds support for "soft bundles" to combine multiple offers (e.g. 3 OSI promo codes together) — to each have their own promo code, instead of forcing all offers in the bundle to share a single code.

Example: if a card bundles 3 offers and you want offer 1 to show "PROMO1", offer 2 to show "PROMO2" and offer 3 to show "PROMO3", you can now do that.
Before, you could only apply one promo code to the whole bundle.

Also included: a small cleanup so a promo code list like " CODE1, CODE2 " (extra spaces, stray commas) is parsed correctly instead of keeping the whitespace as part of the code.

Rules for OSI ↔ promo code pairing:

1. 1 OSI + 1 promo code = unchanged: that code applies to that OSI.
   osi="A" promo="PROMOCODE1" --> A=PROMOCODE1

2. Multiple OSIs + exactly 1 promo code = unchanged: broadcasts to all.
   osi="A,B,C" promo="PROMOCODE1" --> A=PROMOCODE1, B=PROMOCODE1, C=PROMOCODE1

3. Multiple OSIs + 2+ promo codes --> paired by position (1st OSI ↔ 1st code, etc).
   osi="A,B,C" promo="PROMOCODE1,PROMOCODE2,PROMOCODE3" --> A=PROMOCODE1, B=PROMOCODE2, C=PROMOCODE3

4. More OSIs than codes --> extra OSIs get no promo code.
   osi="A,B,C" promo="PROMOCODE1,PROMOCODE2" --> A=PROMOCODE1, B=PROMOCODE2, C=(none)

5. More codes than OSIs --> extra codes are ignored.
   osi="A,B" promo="PROMOCODE1,PROMOCODE2,PROMOCODE3" --> A=PROMOCODE1, B=PROMOCODE2, (PROMOCODE3 ignored)

6. A blank OSI slot drops its paired code too, so later OSIs keep their own code.
   osi="A,,C" promo="PROMOCODE1,PROMOCODE2,PROMOCODE3" --> A=PROMOCODE1, C=PROMOCODE3 (PROMOCODE2 dropped, not shifted onto C)

Test links:
Studio:

Before: https://mas.adobe.com/studio.html?ost=new#fragmentId=c075f0c7-a08d-4e42-8d45-03a5169dd877&page=fragment-editor&path=sandbox
After: https://mwpw-204225--mas--adobecom.aem.live/studio.html?ost=new#fragmentId=c075f0c7-a08d-4e42-8d45-03a5169dd877&maslibs=MWPW-204225&page=fragment-editor&path=sandbox

Preview:
Before: https://main--milo--adobecom.aem.page/merch/mas/preview?fragment-id=c075f0c7-a08d-4e42-8d45-03a5169dd877&content-type=merch-card&locale=en_US
After: https://main--milo--adobecom.aem.page/merch/mas/preview?fragment-id=c075f0c7-a08d-4e42-8d45-03a5169dd877&content-type=merch-card&locale=en_US&maslibs=MWPW-204225

Before:

After:

(It also appears in Axel's extension)

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• C4. PR description contains working Test Page link where the feature can be tested
• C5: you are ready to do a demo from Test Page in PR (bonus: write a working demo script that you'll use on Thursday, you can eventually put in your PR)
• C.6 read your Jira one more time to validate that you've addressed all AC's and nothing is missing

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Test URLs:

• Before: https://main--mas--adobecom.aem.live/
• After: https://mwpw-204225--mas--adobecom.aem.live/

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Commits

• 96b2828 ✅ (latest)
• ea31bdf ✅
• 8cf2c84 ✅
• 78a7137 ✅
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• 6df4748 ✅
• c498179 ✅
• 7dbecac ✅
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• 12ed3cb ✅

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.77%. Comparing base (2f2e131) to head (96b2828).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1195      +/-   ##
==========================================
+ Coverage   90.71%   90.77%   +0.05%     
==========================================
  Files         318      318              
  Lines      101712   101768      +56     
==========================================
+ Hits        92271    92375     +104     
+ Misses       9441     9393      -48     

Files with missing lines	Coverage Δ
web-components/src/checkout.js	100.00% <100.00%> (ø)
web-components/src/merch-card.js	89.85% <100.00%> (+<0.01%)	⬆️
web-components/src/price.js	99.33% <100.00%> (+0.02%)	⬆️
web-components/src/utilities.js	97.92% <100.00%> (+0.31%)	⬆️
web-components/src/wcs.js	97.57% <100.00%> (+0.06%)	⬆️

... and 10 files with indirect coverage changes

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[Axelcureno]

Nice, per-OSI zip is clean and the wcs tests asserting real URLs are great.

Ran your branch with osi="abm,,stock-abm" and promo="P1,P2,P3": wcsOsi comes back length 2, promotionCodes length 3, and stock-abm requests promotion_code=P2 instead of P3. toOfferSelectorIds drops blanks, toPromotionCodes keeps them, and wcs zips by index. Worth pairing before filtering.

Nit: promotionCodes holds undefined entries where the JSDoc says ''.

[Andrei4226]

Nice, per-OSI zip is clean and the wcs tests asserting real URLs are great.

Ran your branch with osi="abm,,stock-abm" and promo="P1,P2,P3": wcsOsi comes back length 2, promotionCodes length 3, and stock-abm requests promotion_code=P2 instead of P3. toOfferSelectorIds drops blanks, toPromotionCodes keeps them, and wcs zips by index. Worth pairing before filtering.

Nit: promotionCodes holds undefined entries where the JSDoc says ''.

Thanks!
I fixed both: pairing OSI and promo codes by index before dropping blanks (toWcsOsiAndPromotionCodes), so stock-abm now correctly gets P3 instead of P2. Also removed the now-unused toOfferSelectorIds in favor of it. Left the undefined/'' nit as-is since it's expected downstream (computePromoStatus resolves a blank code to undefined, which wcs.js already coalesces back to '' via ?? '') and updated the JSDoc to call that out instead of changing the behavior.
Added tests covering these scenarios.

[Axelcureno]

Verified, zipping before the blank filter fixes it: abm,,stock-abm + P1,P2,P3 now gives ['abm','stock-abm'] / ['P1','P3'], toOfferSelectorIds has no callers left, and trailing blanks / extra codes / missing codes all degrade cleanly.

One tiny thing on the nit: computePromoStatus(code).effectivePromoCode ?? '' at the two map sites (price.js:58, checkout.js:71) makes the array actually string[], so the wcs.js:290 JSDoc is true. omitProperties treats '' and undefined the same, so nothing downstream shifts. Otherwise good to go.

[Axelcureno]

Verified above, approving. The ?? '' nit is optional.

Branch is conflicting with main, needs a merge before this can land.

[seanchoi0]

Approving but you should resolve the conflict