Revert avoid unnecessary parentheses change

[makasim]

The change introduced in #63 breaks query like this:

10 - (3 + 3 + 4)

which is transformed into:

10 - 3 + 3 + 4

Those queries produce different results.

Fixes VictoriaMetrics/VictoriaMetrics#10856

---

Summary by cubic

Reverts the optimization that removed parentheses in binary expressions to restore correct evaluation order. Prevents wrong rewrites like 10 - (3 + 3 + 4) → 10 - 3 + 3 + 4 (fixes VictoriaMetrics/VictoriaMetrics#10856).

• Bug Fixes
  • Parser now always adds parentheses around binary operands; removed priority-based elision logic.
  • Updated tests and examples to expect preserved grouping (e.g., (a * b) / c and 100 * (x / y)).

^{Written for commit 4121a48. Summary will update on new commits.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.73%. Comparing base (278b8a2) to head (4121a48).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #72      +/-   ##
==========================================
+ Coverage   89.71%   89.73%   +0.01%     
==========================================
  Files          11       11              
  Lines        2996     2981      -15     
==========================================
- Hits         2688     2675      -13     
+ Misses        210      209       -1     
+ Partials       98       97       -1     

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[f41gh7]

LGTM