v0.3: WebRTC P2P via Pion (Go) + RTCPeerConnection (browser)

Server: unchanged shape, just added a "signal" message type to the
existing /api/send + /api/stream bus. Now carries both "clipboard"
(payload) and "signal" (offer/answer/ICE) over the same envelope.

Client: -rtc flag turns the Go listener into a Pion peer. Posts an SDP
offer at startup, accepts the browser's answer through the signaling
bus, exchanges ICE, then receives clipboard text over a DataChannel
named "tether". On message: writes to OS clipboard same as SSE path.

Web UI: acts as the answerer. Listens for "signal" SSE events, replies
to offers, exchanges ICE. When DataChannel opens, the send button uses
RTCDataChannel.send() instead of POST /api/send — data no longer
traverses the server after pairing. Pill in the header flips
sse → negotiating → rtc to make this visible.

Toolchain: bumped go.mod to go 1.26, switched to pion/webrtc v4 and
prometheus/client_golang v1.23.x.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

go.mod

@@ -1,44 +1,41 @@
 module github.com/pecord/tether
 
-go 1.22
+go 1.26
 
 require (
 	github.com/atotto/clipboard v0.1.4
-	github.com/prometheus/client_golang v1.20.5
+	github.com/pion/webrtc/v4 v4.2.12
+	github.com/prometheus/client_golang v1.23.2
 )
 
 require (
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
-	github.com/davecgh/go-spew v1.1.1 // indirect
-	github.com/google/uuid v1.3.1 // indirect
-	github.com/klauspost/compress v1.17.9 // indirect
+	github.com/google/uuid v1.6.0 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
-	github.com/pion/datachannel v1.5.8 // indirect
-	github.com/pion/dtls/v2 v2.2.12 // indirect
-	github.com/pion/ice/v2 v2.3.38 // indirect
-	github.com/pion/interceptor v0.1.29 // indirect
-	github.com/pion/logging v0.2.2 // indirect
-	github.com/pion/mdns v0.0.12 // indirect
+	github.com/pion/datachannel v1.6.0 // indirect
+	github.com/pion/dtls/v3 v3.1.2 // indirect
+	github.com/pion/ice/v4 v4.2.5 // indirect
+	github.com/pion/interceptor v0.1.44 // indirect
+	github.com/pion/logging v0.2.4 // indirect
+	github.com/pion/mdns/v2 v2.1.0 // indirect
 	github.com/pion/randutil v0.1.0 // indirect
-	github.com/pion/rtcp v1.2.14 // indirect
-	github.com/pion/rtp v1.8.7 // indirect
-	github.com/pion/sctp v1.8.19 // indirect
-	github.com/pion/sdp/v3 v3.0.9 // indirect
-	github.com/pion/srtp/v2 v2.0.20 // indirect
-	github.com/pion/stun v0.6.1 // indirect
-	github.com/pion/transport/v2 v2.2.10 // indirect
-	github.com/pion/turn/v2 v2.1.6 // indirect
-	github.com/pion/webrtc/v3 v3.3.6 // indirect
-	github.com/pmezard/go-difflib v1.0.0 // indirect
-	github.com/prometheus/client_model v0.6.1 // indirect
-	github.com/prometheus/common v0.55.0 // indirect
-	github.com/prometheus/procfs v0.15.1 // indirect
-	github.com/stretchr/testify v1.9.0 // indirect
-	github.com/wlynxg/anet v0.0.3 // indirect
-	golang.org/x/crypto v0.24.0 // indirect
-	golang.org/x/net v0.26.0 // indirect
-	golang.org/x/sys v0.22.0 // indirect
-	google.golang.org/protobuf v1.34.2 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
+	github.com/pion/rtcp v1.2.16 // indirect
+	github.com/pion/rtp v1.10.1 // indirect
+	github.com/pion/sctp v1.9.5 // indirect
+	github.com/pion/sdp/v3 v3.0.18 // indirect
+	github.com/pion/srtp/v3 v3.0.10 // indirect
+	github.com/pion/stun/v3 v3.1.2 // indirect
+	github.com/pion/transport/v4 v4.0.1 // indirect
+	github.com/pion/turn/v5 v5.0.3 // indirect
+	github.com/prometheus/client_model v0.6.2 // indirect
+	github.com/prometheus/common v0.66.1 // indirect
+	github.com/prometheus/procfs v0.16.1 // indirect
+	github.com/wlynxg/anet v0.0.5 // indirect
+	go.yaml.in/yaml/v2 v2.4.2 // indirect
+	golang.org/x/crypto v0.48.0 // indirect
+	golang.org/x/net v0.50.0 // indirect
+	golang.org/x/sys v0.41.0 // indirect
+	golang.org/x/time v0.14.0 // indirect
+	google.golang.org/protobuf v1.36.8 // indirect
 )