fix(pinia-orm): declare vue as peer dependency

[CodeDredd]

Why the reported bundle size was inflated

The setup store support (#1905, 953826a9) added import { ref } from 'vue' to useDataStore — but vue was never declared as a peer dependency. Consequences:

1. size-limit only auto-ignores peer dependencies, so it bundled vue's reactivity system into the measurement: reported 16.18 kB brotli instead of the real 11.75 kB. Real apps were never affected (vue is in every pinia app anyway and gets deduplicated).
2. Package managers couldn't validate/warn about the vue version pinia-orm actually requires.

Fix

• vue >= 3.4 declared as peer dependency (pinia already requires vue as peer, so nothing changes at install time)
• index size limit lowered from the recently-raised 16.5 kB back to 12 kB — the measurement now reflects what users actually pay

Suite green (430 tests), size check green at 11.75/12 kB.

Related: #2051 tracks the structural size reductions (tree-shakeable relations).

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.34%. Comparing base (4ff579b) to head (3bceaa4).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2052      +/-   ##
==========================================
+ Coverage   99.24%   99.34%   +0.09%     
==========================================
  Files          83       83              
  Lines        3185     3185              
  Branches      562      562              
==========================================
+ Hits         3161     3164       +3     
+ Misses         17       15       -2     
+ Partials        7        6       -1     

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