fix(runtime-dom): respect current select model type

[zongxi1115]

Summary

Fixes #15009, v-model on <select multiple> so it respects the current model collection type when the bound value switches between Array and Set.

vModelSelect previously captured isSet(value) once in the directive created hook. If the model started as an Array and was later replaced with a Set, the next user-triggered change still emitted an Array. The reverse direction had the same stale-type behavior.

This updates the select directive to read the current model value when handling change events, matching the approach already used by checkbox v-model.

Reproduction

1. Bind <select multiple v-model> to an Array.
2. Replace the model with a Set at runtime.
3. Change the selection in the UI.
4. The emitted value becomes an Array again instead of staying a Set.

The same issue also happens in reverse when switching from Set to Array.

Test

Added a regression test covering both Array -> Set and Set -> Array.

Summary by CodeRabbit

• Bug Fixes
  • Fixed multiple-select bindings so they keep using the current model type when selections change.
  • Improved consistency when switching between Array and Set values, so selected options are preserved and updated correctly.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 7a7bf04a-79cf-434f-bfd6-6638cced07a0

📥 Commits

Reviewing files that changed from the base of the PR and between c0606e9 and 154e213.

📒 Files selected for processing (2)

• packages/runtime-dom/__tests__/directives/vModel.spec.ts
• packages/runtime-dom/src/directives/vModel.ts

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📝 Walkthrough

Walkthrough

v-model for <select multiple> now tracks the current model value on the element, uses that snapshot during change handling, and adds a test covering Array-to-Set and Set-to-Array switching.

Changes

Select multiple v-model collection type tracking

Layer / File(s)	Summary
Element-backed model snapshot packages/runtime-dom/src/directives/vModel.ts	The select multiple directive stores the current model value on the element, reads it when handling changes, and refreshes it before updates.
Array and Set switching test packages/runtime-dom/__tests__/directives/vModel.spec.ts	A new test switches the backing model between Array and Set and checks the emitted value matches the active collection type.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Suggested labels

:hammer: p3-minor-bug

Poem

A bunny hopped by, ears held high,
"Array or Set?" the v-model sighed.
I nudged the select, then watched it play,
And kept the right kind all the way.
🐇✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main fix: select v-model now respects the current model type.
Linked Issues check	✅ Passed	The directive change and regression test address the reported Array/Set type staleness in both directions.
Out of Scope Changes check	✅ Passed	The PR stays focused on the select v-model bug fix and its test coverage, with no unrelated changes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[github-actions]

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	107 kB (+44 B)	40.3 kB (+20 B)	36.2 kB (+2 B)
vue.global.prod.js	165 kB (+44 B)	60.4 kB (+14 B)	53.7 kB (+10 B)

Usages

Name	Size	Gzip	Brotli
createApp (CAPI only)	49 kB	19 kB	17.4 kB
createApp	57.1 kB	22.1 kB	20.2 kB
createSSRApp	61.6 kB	23.9 kB	21.8 kB
defineCustomElement	63.3 kB	24 kB	21.9 kB
overall	71.9 kB	27.5 kB	25.1 kB

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commit: 154e213

[edison1105]

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