[drahnr]

Replaces rouille with warp as our primary request/response handler framework.

Part of porting changes from cachepot #1620
The original PR is here paritytech/cachepot#131

Supersedes #2241 with all fixes included.

Initial porting was done by @Saruniks
Original work was done by @montekki

[codecov-commenter]

Codecov Report

❌ Patch coverage is 51.43678% with 169 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.34%. Comparing base (33d12fb) to head (843c3bc).

Files with missing lines	Patch %	Lines
tests/harness/mod.rs	0.00%	83 Missing ⚠️
tests/dist.rs	0.00%	58 Missing ⚠️
src/bin/sccache-dist/main.rs	11.11%	16 Missing ⚠️
src/dist/client_auth.rs	0.00%	9 Missing ⚠️
src/bin/sccache-dist/token_check.rs	96.80%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3009      +/-   ##
==========================================
- Coverage   78.81%   78.34%   -0.48%     
==========================================
  Files          75       75              
  Lines       45354    46826    +1472     
==========================================
+ Hits        35745    36684     +939     
- Misses       9609    10142     +533     

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[Copilot]

🟡 Changes recommended

Blocking build/cache operations and unbounded upload buffering risk server stalls and memory exhaustion, while Accept negotiation and upload timing introduce compatibility and job-expiration regressions.

1 open issue

• Synchronous build and cache work blocks Tokio workers · New

What changed in this PR

Migrates sccache’s distributed HTTP services from Rouille to Warp, continuing the cachepot port tracked in #1620 and superseding #2241.

Changes:

• Converts distributed handlers, authentication requests, and server startup to async execution.
• Adds HTTP regression tests and adapts distributed integration tests to Tokio.
• Also fixes NVCC executable lookup when dry-run output omits PATH, with regression tests.

File	Description
tests/​harness/​mod.rs	Uses async server tasks, HTTP checks, and readiness polling.
tests/​dist.rs	Converts distributed tests to async execution and serializes them.
src/​util.rs	Replaces the blocking HTTP client helper with an async client.
src/​lib.rs	Removes the Rouille macro import.
src/​dist/​mod.rs	Updates distributed traits and reader bounds for async handlers.
src/​dist/​http.rs	Implements Warp routes, async requests, and HTTP regression tests.
src/​dist/​client_auth.rs	Makes OAuth token exchange asynchronous.
src/​compiler/​nvcc.rs	Adds inherited PATH fallback and executable-lookup tests.
src/​bin/​sccache-dist/​token_check.rs	Converts remote token checks to async and adds tests.
src/​bin/​sccache-dist/​main.rs	Integrates Tokio runtimes and async distributed handlers.
Cargo.toml	Replaces Rouille with Warp and updates dependency features.
Cargo.lock	Records the updated dependency graph.

_{Review effort: Balanced}