Move pipe and socket URL handling to net/url

[samuv]

Summary

Follow-up to #5201 (review thread). Stacked on socker-windows; will rebase onto main once #5201 merges. Sibling to #5214.

Replaces prefix-and-trim string handling with net/url.Parse on both producer (socketURL) and consumer (HTTPClientForURL, ParseNamedPipeURL, ParseUnixSocketPath) sides so pipe and socket addresses round-trip through one library and one set of rules.

The change includes one real bug fix: socketURL previously emitted unix://C:\path\thv.sock for Windows AF_UNIX paths, which url.Parse rejects with invalid port ":\\path\\thv.sock". The dispatcher only worked because it used strings.TrimPrefix. New behavior emits unix:///C:%5Cpath%5Cthv.sock, which round-trips cleanly. Round-trip is now exercised by TestSocketURL_RoundTrip_Unix and TestSocketURL_RoundTrip_NamedPipe.

Other improvements that fall out of the migration:

• Case-insensitive scheme dispatch — NPIPE://x routes the same arm as npipe://x because url.Parse lowercases the scheme during parsing. Pinned by TestHTTPClientForURL_SchemeDispatchCaseInsensitive.
• Case-insensitive pipe-name normalization — npipe://Thv-API resolves to \\.\pipe\thv-api via strings.ToLower(u.Hostname()); matches the kernel's case-insensitive pipe namespace.
• Length cap on pipe names (247 chars, the CreateNamedPipeW lpName limit after the \\.\pipe\ prefix).
• Reserved-name rejection for legacy Windows device names (CON, NUL, PRN, AUX, COM1-9, LPT1-9).
• Positive charset of [A-Za-z0-9._-]+ for pipe names — replaces the over-eager strings.Contains(name, "..") guard which rejected legitimate names like my..api.
• Stricter URL shape: ParseNamedPipeURL rejects pipe URLs with non-empty path / query / fragment / userinfo / port; ParseUnixSocketPath rejects unix URLs with non-empty authority.

Addresses inline review comments 3201085366 (ParseNamedPipeURL migration), 3201085375 (dispatcher migration), and 3201085383 (socketURL / ParseUnixSocketPath migration + Windows AF_UNIX bug).

Type of change

• Bug fix (Windows AF_UNIX URL round-trip)
• Code quality / hardening

Test plan

• Unit tests (go test ./pkg/api/... ./pkg/server/discovery/...) — green on macOS; new round-trip tests, scheme-case test, reserved-name tests, length-cap test, and shape-rejection cases all pass.
• task lint-fix — 0 issues.
• GOOS=windows go vet and GOOS=windows go test -c -o /dev/null for both packages — both clean.

Does this introduce a user-facing change?

Yes (Windows-only). On Windows, socketURL for AF_UNIX paths now emits a percent-encoded URL form. The discovery file is local per-user and overwritten on every thv serve startup, so there is no on-disk migration concern. POSIX paths like /tmp/thv.sock produce identical output before and after.

Made with Cursor

[codecov]

Codecov Report

❌ Patch coverage is 77.14286% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 67.77%. Comparing base (d5337ec) to head (24b1dfe).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/server/discovery/health.go	76.47%	4 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5215      +/-   ##
==========================================
- Coverage   67.79%   67.77%   -0.03%     
==========================================
  Files         608      610       +2     
  Lines       62234    62288      +54     
==========================================
+ Hits        42191    42214      +23     
- Misses      16869    16899      +30     
- Partials     3174     3175       +1     

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