feat(gooserelay): add GooseRelay outbound under protocol/hiddify/gooserelay

[hiddifyafk]

Summary

Adds a new gooserelay outbound that wraps the GooseRelayVPN carrier — domain-fronted HTTPS to a Google Apps Script endpoint, AES-256-GCM-encrypted frames forwarded to a VPS — as a native Hiddify-only sing-box outbound. Lives at protocol/hiddify/gooserelay/ next to dnstt, registered through the //H block in constant/proxy.go and include/registry.go. Zero touch to vanilla protocol/ paths so upstream merges stay clean.

What's in the JSON config

{
  "type": "gooserelay",
  "tag": "goose-out",
  "script_keys": ["AKfycbx<deployment-id>"],
  "tunnel_key": "<64-char hex AES-256 key>",
  "google_host": "216.239.38.120:443",
  "sni": ["www.google.com"],
  "udp_over_tcp": {"enabled": false},
  "handshake_timeout": "10s"
}

script_keys are deployment IDs (not full URLs); the outbound builds the https://script.google.com/macros/s/.../exec URLs internally.

Upstream fork dependency

Depends on a Hiddify fork of Kianmhz/GooseRelayVPN because the carrier's reusable types live in internal/* upstream. The fork ships a single thin wrapper package (goose/sdk.go) that re-exports Config, FrontingConfig, and a Client with the four methods this outbound actually needs (Run, Diagnose, Shutdown, Dial). The fork's tree is otherwise byte-identical to upstream so future upstream merges land conflict-free.

go.mod changes:

• require github.com/kianmhz/GooseRelayVPN v0.0.0-20260429125124-0e68c2a3ae4c
• replace github.com/kianmhz/GooseRelayVPN => github.com/hiddify/GooseRelayVPN v0.0.0-20260429125124-0e68c2a3ae4c

Pseudo-version pins to merge commit 0e68c2a3ae4c on hiddify/GooseRelayVPN main (PR #2 there: switch to SDK wrapper).

Architecture notes

• One *goose.Client per outbound. The carrier handles per-endpoint round-robin and exponential-backoff blacklisting internally, so we don't need a tester.go analog of the dnstt outbound. Significantly less code than dnstt for equivalent reliability.
• Multi-endpoint diagnose at startup. Each script_key is probed concurrently via a throwaway one-endpoint *goose.Client.Diagnose(); the outbound flips ready on the first success and cancels remaining probes. Mirrors dnstt's "any healthy resolver wins" semantics.
• Lifecycle. PostStart launches client.Run(runCtx) and the diagnose probes (both tied to the same runCtx so Close() cancels them). Close() calls goose.Client.Shutdown first to send graceful RSTs, then cancels runCtx to stop the workers.
• TCP-only at the carrier level. UDP works via uot.Client when udp_over_tcp.enabled is set, using the outbound itself as the underlying TCP dialer.

Commits

Self-contained, ordered to minimize churn in diagnoseAndMarkReady:

#	SHA	Subject
1	2d8f97b3	feat: add GooseRelay outbound under protocol/hiddify/gooserelay
2	6bc48c0b	style(constant): re-align //H comment column after adding TypeGooseRelay
3	c7cf64d6	refactor(gooserelay): rename defaultHandshakeBudget → defaultDiagnoseTimeout
4	8bf7a0a1	fix(gooserelay): check tunnel_key length before attempting hex decode
5	25a163de	fix(gooserelay): reject script_keys containing URL separators
6	1a01efb5	refactor(gooserelay): use context-aware logger methods
7	63f71e49	fix(gooserelay): tie diagnose probe to runCtx so Close cancels it
8	fbd73fb0	feat(gooserelay): probe all script_keys concurrently, ready on first pass
9	71acba52	test(gooserelay): add option-validation table tests
10	a73acd51	refactor(gooserelay): switch to upstream's goose SDK package

Commits 2–10 are review-fixes/migration on top of commit 1. Happy to squash on merge if preferred.

Test plan

• go build ./... — passes (only the unrelated macOS -lobjc linker warning).
• go test -race ./protocol/hiddify/gooserelay/... — passes (10 sub-cases in TestNew_OptionValidation covering missing/invalid script_keys and tunnel_key, URL-separator rejection, and the happy path).
• go vet ./protocol/hiddify/gooserelay/... — clean.
• Runtime check. Built cmd/sing-box, ran sing-box check -c <config> against:
  • valid minimal gooserelay config → exits 0 ✓
  • tunnel_key length 8 → tunnel_key must be 64 hex characters (AES-256) ✓
  • script_keys[0] = "abc/def" → URL separator (/?#); paste the deployment ID only ✓
  • missing script_keys → script_keys is required ✓
• End-to-end (out of scope for this PR). Requires deploying the GooseRelayVPN Apps Script + running cmd/server of the fork on a VPS, then pointing real script_keys + tunnel_key at it. The outbound is structurally complete; this is just a deployment step the operator runs.

Reviewer notes

• Opened from hiddifyafk/hiddify-sing-box because hiddifyafk lacks push access on the org repo (same constraint hit on the GooseRelayVPN fork). Mirroring the workflow used for PR update to latest #1/new: add KDE set system proxy support #2 there.
• Display name in ProxyDisplayName: GooseRelay — single-token style matching DNSTT.
• The goose/sdk.go wrapper currently uses type aliases (type Config = carrier.Config), which keeps us coupled to upstream's struct shape. If upstream renames a Config field, this PR's outbound code may need to follow. Concrete-struct wrappers would insulate us further; deferred until upstream signals instability.

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