fix: skip deduplication for upgrade requests

[Ram-blip]

This relates to...

The deduplicate interceptor currently treats upgrade-bearing requests as ordinary safe-method requests. Since Dispatcher.upgrade() dispatches a GET with an upgrade option, the request can enter the normal response-deduplication path.

A successful protocol upgrade completes through onRequestUpgrade and transfers an upgraded socket instead of following the normal onResponseStart → onResponseData → onResponseEnd lifecycle. As a result, the pending deduplication entry is not removed, and later matching requests can attach to stale state without being dispatched or settled.

Rationale

Protocol upgrades are stateful operations and cannot share or replay a single upgraded transport across independent callers.

Upgrade-bearing requests should therefore bypass response deduplication before key generation and pending-request lookup. This also prevents collisions between an ordinary GET and an otherwise identical upgrade-bearing GET.

Changes

• Skip deduplication for upgrade-bearing requests.
• Preserve existing behavior for ordinary requests where upgrade is absent or falsey.
• Add a deterministic regression test proving that an upgrade request is dispatched independently from a matching pending GET.

Features

N/A

Bug Fixes

• Prevent upgrade requests from entering the ordinary response-deduplication lifecycle.
• Prevent stale pending entries after a successful protocol upgrade.
• Prevent later matching requests from attaching to an already completed upgrade.
• Prevent ordinary GET and upgrade-bearing GET requests from colliding in the deduplication map.

Breaking Changes and Deprecations

None.

Status

• I have read and agreed to the Developer's Certificate of Origin
• Tested
• Benchmarked (optional)
• Documented
• Review ready
• In review
• Merge ready

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.47%. Comparing base (21a8e1e) to head (772bdd0).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5593      +/-   ##
==========================================
- Coverage   93.47%   93.47%   -0.01%     
==========================================
  Files         110      110              
  Lines       38238    38238              
==========================================
- Hits        35744    35742       -2     
- Misses       2494     2496       +2     

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