Re-vendor the canonical files from sneak/prompts at dd4027b (closes #112)

The shared files are fetched from sneak/prompts dd4027b, with this
repository's own entries after the shared content in .gitignore,
.editorconfig and .dockerignore.

Lint and tests are Dockerfile phases (golangci-lint v2.14.0, Debian Go
1.24.13) that the build stage depends on, and the Makefile targets call
the script/ entrypoints. make fmt also formats Markdown with prettier.

Fixes for the new lint findings: the auth cookie is always Secure, an
IRC connection's relay goroutine stops when the connection closes, and
repeated strings are constants.

Model: opus-5-5

internal/ircserver/integration_test.go

@@ -282,6 +282,7 @@ func TestIntegrationTwoClients(t *testing.T) {
 
 	// Both nicks should appear in the name list.
 	foundBothNames := false
+
 	for _, line := range aliceNames {
 		if strings.Contains(line, " 353 ") &&
 			strings.Contains(line, "alice") &&
@@ -671,6 +672,7 @@ func TestIntegrationTwoClients(t *testing.T) {
 	})
 
 	foundPartErr := false
+
 	for _, line := range bobPartFail {
 		if strings.Contains(line, " 403 ") ||
 			strings.Contains(line, " 442 ") {
@@ -833,6 +835,7 @@ func TestIntegrationModeModerated(t *testing.T) {
 	})
 
 	foundModErr := false
+
 	for _, line := range bobLines {
 		if strings.Contains(line, " 404 ") ||
 			strings.Contains(line, " 482 ") {
@@ -859,6 +862,7 @@ func TestIntegrationModeModerated(t *testing.T) {
 	})
 
 	bob.send("PRIVMSG #modtest :voiced message")
+
 	aliceLines := alice.readUntil(func(l string) bool {
 		return strings.Contains(l, "voiced message")
 	})