feat: register cockatrice:// and cockatrice-oracle:// protocol handlers

Adds OS-level URL-scheme handlers so users can click a link in a browser,
chat client, or third-party tool to launch Cockatrice straight into a
server / game / Oracle update.

Supported URL forms:
  cockatrice://joingame?hostname=H&port=P&roomid=R&gameid=G[&spectate=1]
  cockatrice-oracle://update[?spoilers=1]

Credentials passed via URL (username/password query params) are deliberately
ignored — URLs leak through shell history, browser history, EDR capture, etc.
If the target server requires auth and no saved credentials match, the Connect
dialog opens pre-filled with the URL's host/port so the user types their
password locally.

OS integration
- Linux: MimeType=x-scheme-handler/cockatrice (and -oracle) added to the
  .desktop files; Exec=cockatrice %u passes the URL through.
- Windows: NSIS installer writes HKCR\cockatrice and HKCR\cockatrice-oracle
  registry entries; uninstaller removes them.
- macOS: per-app Info.cockatrice.plist / Info.oracle.plist declare
  CFBundleURLTypes; a QFileOpenEvent filter is installed on QApplication
  before any nested event loop so cold-start URLs aren't lost.

New abstractions
- Intent (libcockatrice_utility/libcockatrice/utility/intent.h): abstract base
  for chained async actions.  Guarantees finished() fires at most once,
  execute() is idempotent, self-deletes via deleteLater, and
  startTimeoutSafetyNet() arms a configurable per-stage deadline.  Concrete
  intents (IntentConnectToServer, IntentLogin, IntentJoinServerRoom,
  IntentJoinServerGame) compose the joingame flow via UrlParser.
- SingleInstanceManager: async per-user local-socket primary/secondary
  handshake; URL forwarded from secondary to primary with QDataStream framing
  both ways.  shared_ptr-backed resolved flag survives every lambda capture.
- UrlSchemeEventFilter (new libcockatrice_utility_gui sibling library): QObject
  event filter that translates macOS QFileOpenEvent into a urlReceived(QString)
  signal.  Lives in its own Gui-bearing lib so libcockatrice_utility stays
  Core+Network only and doesn't drag Qt::Gui into servatrice.
- UrlUtils (header-only): pure URL parsing, fully unit-tested.

Wiring
- MainWindow::handleUrl(QString) — single entry point for any URL source.
- DlgConnect::prefillNewHost(host, port) — pre-fills new-host inputs.
- ServersSettings::findSavedCredsByHostPort — case-insensitive saved-creds
  lookup.
- TabSupervisor::requestJoinRoom + roomJoinedById / roomJoinFailedById signals,
  TabServer::roomAlreadyJoined for the short-circuit "already in this room"
  path — single source of truth for duplicate-join handling.

Tests
- 36 new unit tests across four single-purpose targets in tests/:
  - url_utils_test (22 tests) — scheme matching, port/room/game validation,
    spectator flag, credentials ignored, case-insensitivity.
  - url_scheme_event_filter_test (3 tests) — QFileOpenEvent capture.
  - intent_test (7 tests) — self-delete, abort propagation, parent-destruction-
    mid-flight, finish-once gate, execute() idempotence.
  - single_instance_manager_test (4 tests) — per-user socket naming, becoming-
    primary alone, forwarding to an existing primary, single-emission of
    roleResolved.

Build tooling (incidental)
- Dockerfile.format, docker-compose.format.yml, Makefile — a docker-based
  runner for format.sh that mirrors CI's desktop-lint step.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cmake/FindQtRuntime.cmake

@@ -115,4 +115,10 @@ string(REGEX REPLACE "([^;]+)" "${COCKATRICE_QT_VERSION_NAME}::\\1" TEST_QT_MODU
 # Core-only export (useful for headless libs)
 set(QT_CORE_MODULE "${COCKATRICE_QT_VERSION_NAME}::Core")
 
+# Network-only export (useful for network-dependent libs that don't need GUI)
+set(QT_NETWORK_MODULE "${COCKATRICE_QT_VERSION_NAME}::Network")
+
+# GUI export
+set(QT_GUI_MODULE "${COCKATRICE_QT_VERSION_NAME}::Gui")
+
 message(STATUS "Found Qt ${${COCKATRICE_QT_VERSION_NAME}_VERSION} at: ${${COCKATRICE_QT_VERSION_NAME}_DIR}")

cmake/Info.cockatrice.plist

@@ -34,5 +34,16 @@
     <string>${MACOSX_BUNDLE_COPYRIGHT}</string>
     <key>NSHighResolutionCapable</key>
     <true/>
+    <key>CFBundleURLTypes</key>
+    <array>
+        <dict>
+            <key>CFBundleURLName</key>
+            <string>com.cockatrice.Cockatrice.url</string>
+            <key>CFBundleURLSchemes</key>
+            <array>
+                <string>cockatrice</string>
+            </array>
+        </dict>
+    </array>
 </dict>
 </plist>

cmake/Info.oracle.plist

@@ -0,0 +1,49 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+    <key>CFBundleDevelopmentRegion</key>
+    <string>English</string>
+    <key>CFBundleExecutable</key>
+    <string>${MACOSX_BUNDLE_EXECUTABLE_NAME}</string>
+    <key>CFBundleGetInfoString</key>
+    <string>${MACOSX_BUNDLE_INFO_STRING}</string>
+    <key>CFBundleIconFile</key>
+    <string>${MACOSX_BUNDLE_ICON_FILE}</string>
+    <key>CFBundleIdentifier</key>
+    <string>${MACOSX_BUNDLE_GUI_IDENTIFIER}</string>
+    <key>CFBundleInfoDictionaryVersion</key>
+    <string>6.0</string>
+    <key>CFBundleLongVersionString</key>
+    <string>${MACOSX_BUNDLE_LONG_VERSION_STRING}</string>
+    <key>CFBundleName</key>
+    <string>${MACOSX_BUNDLE_BUNDLE_NAME}</string>
+    <key>CFBundlePackageType</key>
+    <string>APPL</string>
+    <key>CFBundleShortVersionString</key>
+    <string>${MACOSX_BUNDLE_SHORT_VERSION_STRING}</string>
+    <key>CFBundleSignature</key>
+    <string>????</string>
+    <key>CFBundleVersion</key>
+    <string>${MACOSX_BUNDLE_BUNDLE_VERSION}</string>
+    <key>CSResourcesFileMapped</key>
+    <true/>
+    <key>LSRequiresCarbon</key>
+    <true/>
+    <key>NSHumanReadableCopyright</key>
+    <string>${MACOSX_BUNDLE_COPYRIGHT}</string>
+    <key>NSHighResolutionCapable</key>
+    <true/>
+    <key>CFBundleURLTypes</key>
+    <array>
+        <dict>
+            <key>CFBundleURLName</key>
+            <string>com.cockatrice.Oracle.url</string>
+            <key>CFBundleURLSchemes</key>
+            <array>
+                <string>cockatrice-oracle</string>
+            </array>
+        </dict>
+    </array>
+</dict>
+</plist>

cmake/NSIS.template.in

@@ -344,6 +344,16 @@ ${If} $PortableMode = 0
 	WriteRegDWORD HKLM "Software\Microsoft\Windows\CurrentVersion\Uninstall\Cockatrice" "VersionMajor" "@CPACK_PACKAGE_VERSION_MAJOR@"
 	WriteRegDWORD HKLM "Software\Microsoft\Windows\CurrentVersion\Uninstall\Cockatrice" "VersionMinor" "@CPACK_PACKAGE_VERSION_MINOR@"
 
+	; Register cockatrice:// URI scheme
+	WriteRegStr HKCR "cockatrice" "" "URL:Cockatrice Protocol"
+	WriteRegStr HKCR "cockatrice" "URL Protocol" ""
+	WriteRegStr HKCR "cockatrice\shell\open\command" "" '"$INSTDIR\cockatrice.exe" "%1"'
+
+	; Register cockatrice-oracle:// URI scheme
+	WriteRegStr HKCR "cockatrice-oracle" "" "URL:Cockatrice Oracle Protocol"
+	WriteRegStr HKCR "cockatrice-oracle" "URL Protocol" ""
+	WriteRegStr HKCR "cockatrice-oracle\shell\open\command" "" '"$INSTDIR\oracle.exe" "%1"'
+
 	IfFileExists "$INSTDIR\vc_redist.x86.exe" VcRedist86Exists PastVcRedist86Check
 	VcRedist86Exists:
 		ExecWait '"$INSTDIR\vc_redist.x86.exe" /passive /norestart'
@@ -401,6 +411,8 @@ Section "un.Application" UnSecApplication
 	RMDir "$SMPROGRAMS\Cockatrice"
 
 	DeleteRegKey HKLM "Software\Microsoft\Windows\CurrentVersion\Uninstall\Cockatrice"
+	DeleteRegKey HKCR "cockatrice"
+	DeleteRegKey HKCR "cockatrice-oracle"
 SectionEnd
 
 ; unselected because it is /o