## Title

Adopt row-based 7x8 sprite animation semantics with backward-compatible state aliases.

## Severity

P2

## Summary

Standardize `sprite.png` packs so each of the 7 rows maps to semantic animation groups, while
keeping runtime compatibility with existing state names (`active`, `success`, `error`).

## Scope

- `assets/sprite-packs/{default,ferris,demogorgon}/manifest.json`
- `crates/sprimo-runtime-core/src/lib.rs`
- `crates/sprimo-app/src/main.rs`
- docs:
  - `docs/SPRITE_PACK_SCHEMA.md`
  - `docs/TAURI_FRONTEND_DESIGN.md`

## Row Mapping Contract

- row 1 (`0..7`): `idle`
- row 2 (`8..15`): `happy`, `love`, alias `active`
- row 3 (`16..23`): `excited`, `celebrate`, alias `success`
- row 4 (`24..31`): `sleepy`, `snoring`
- row 5 (`32..39`): `working`
- row 6 (`40..47`): `angry`, `surprised`, `shy`, alias `error`
- row 7 (`48..55`): `dragging`

One-shot defaults:

- `celebrate` and `success`: one-shot
- all others: loop

## Implementation Notes

1. Runtime state mapping updated:
- `Dragging` now maps to `"dragging"` instead of `"idle"` in runtime-core and Bevy frontend.
2. All bundled sprite-pack manifests now expose row-based names and compatibility aliases.
3. Added runtime-core unit test to confirm `SetState::Dragging` selects `"dragging"`.
4. Updated schema/design docs to formalize the row convention.

## Verification

### Commands Run

- [x] `cargo test -p sprimo-runtime-core`
- [x] `cargo check -p sprimo-tauri`
- [x] `cargo check -p sprimo-app`

### Result

- Status: `Fix Implemented`
- Notes: packaged runtime visual verification pending.