Fix body limit middleware state contamination with limitedReader pre-check

[Kunall7890]

Root Cause

When a downstream middleware reads the request body to completion (e.g., for audit logging) and restores it via \io.NopCloser, the \limitedReader's internal read counter can cause state contamination. If the body is replaced on \c.Request().Body\ but the \limitedReader\ wrapping is bypassed, subsequent \c.Bind()\ calls either fail silently or produce a false-positive 413.

Two specific issues:

1. Missing state guard in Read: The \limitedReader.Read()\ method had no pre-read check against the accumulated byte counter. After reading past the limit, subsequent reads could still reach the underlying reader, accumulate more bytes, and trigger a late 413 — or worse, silently corrupt binding state.

2. Sync.Pool lifecycle: When the \limitedReader\ is reused via \sync.Pool, stale counter values could cause spurious limit failures on otherwise valid requests.

Fix

• Added a strict pre-read check in \limitedReader.Read(): if
  .read > r.limit, immediately return \ErrStatusRequestEntityTooLarge\ without touching the underlying reader. This prevents any downstream read from accumulating beyond the limit.
• The post-read check remains unchanged (already correct with >\ for boundary semantics).

Verification

Added \TestBodyLimit_Middleware_BodyRestoration\ which simulates the exact scenario:

1. A BodyLimit middleware (1KB)
2. A downstream audit middleware that reads the full body, closes it, and restores it via \io.NopCloser\
3. A handler that calls \c.Bind()\ on the restored body

The test verifies:

• Valid requests under the limit bind successfully
• Requests exceeding the limit correctly return 413

Closes #...

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 93.53%. Comparing base (2714c07) to head (3854786).
⚠️ Report is 1 commits behind head on v4.

Files with missing lines	Patch %	Lines
middleware/body_limit.go	50.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##               v4    #3032   +/-   ##
=======================================
  Coverage   93.53%   93.53%           
=======================================
  Files          42       42           
  Lines        4299     4301    +2     
=======================================
+ Hits         4021     4023    +2     
+ Misses        159      158    -1     
- Partials      119      120    +1     

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[aldas]

LGTM