fix(player): keep origin save bound and surface save slots in v2 EmulatorJS

[gantoine]

Description

Two related fixes to the v2 EmulatorJS player, both driven by the fact that the web player writes save files without a slot and could silently orphan a named-slot save.

1. Decouple save-file and savestate selection (behavior fix)

Previously, selecting (or auto-selecting) a savestate force-deselected the save file, and vice versa. When any compatible savestate existed, the config screen defaulted to the States tab and nulled the save. The consequence: "Save & Quit" then POSTed a brand-new slot-less save file instead of PUTting back to the named-slot save the session started from, so device-sync clients filtering by a named slot never saw that session's progress.

Now save and state are independent. The visible tab still defaults to States when a compatible state exists (quick-resume preserved), but the origin save stays bound to saveRef, so "Save & Quit" updates it in place. Both :save and :state are passed to the engine, which already supports loading save-then-state, so no v1 engine change was required.

2. Surface the save slot (visibility)

Added a brand-toned slot chip (SLOT · <name>) wherever a save renders:

• AssetList (pre-game save list + GameDetails "Save data" subtab)
• AssetPreview (the "resume from save" preview)
• AssetCard (the in-game SelectSaveDialog picker)

Guarded with 'slot' in asset && asset.slot, so states (no slot column) and slot-less web saves render nothing. Adds the play.slot key across all 18 locales and wires slot into the story fixtures.

v1 (frozen) is left untouched; the change is v2-only.

Checklist

• I've tested the changes locally
• I've updated relevant comments
• I've assigned reviewers for this PR
• I've added unit tests that cover the changes

Verification: vue-tsc typecheck clean; i18n parity + sorted checks pass; Storybook composeStories tests 363 passed; trunk fmt + trunk check on all changed files clean. Not verified in a live emulator session (requires a real ROM + running backend).

Screenshots (if applicable)

Slot chips are visible in the AssetList / AssetCard / AssetPreview Storybook stories (fixtures now include a mix of named-slot and slot-less saves).

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AI assistance disclosure

This change was implemented with AI assistance (Claude Code). The AI investigated the save/state wiring, wrote the code, translations, and story fixtures, and ran the verification steps above. All changes were directed and reviewed by the author.

🤖 Generated with Claude Code

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[greptile-apps]

Greptile Summary

This PR keeps saves bound while loading states and displays named save slots in the v2 player. The main changes are:

• Independent save and savestate selection in EmulatorJS.
• Slot tags in asset cards, previews, and lists.
• Slot translations across all supported locales.
• Updated Storybook save fixtures.

Confidence Score: 4/5

Automatic dual selection can overwrite an unrelated named-slot save.

• The slot tags and locale additions follow the existing component contracts.
• A state session can write its SRAM into user_saves[0] without the user selecting that save.
• The save binding needs an explicit or reliable association before it is used for PUT updates.

frontend/src/v2/views/Player/EmulatorJS.vue

Important Files Changed

Filename	Overview
frontend/src/v2/views/Player/EmulatorJS.vue	Allows a save and state to remain selected together, but can bind an unrelated first save as the write target.
frontend/src/v2/components/Player/AssetCard.vue	Adds a guarded slot tag to save cards.
frontend/src/v2/components/Player/AssetPreview.vue	Adds slot metadata to the selected-save preview.
frontend/src/v2/components/shared/AssetList.vue	Displays named slots for save assets while excluding states and slot-less saves.
frontend/src/locales/en_US/play.json	Adds the slot label mirrored across the changed locale files.

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