feat: add MCP endpoint exposing calendar tools over Streamable HTTP

Adds a POST /mcp endpoint (github.com/modelcontextprotocol/go-sdk) with
three tools mirroring the existing /calendar logic: get_calendar_today,
get_calendar_for_date and get_holidays. Bumps go.mod to Go 1.25 (required
by the SDK) and vendors the new dependencies. Also fixes an unanchored
.gitignore rule ("domogeek") that was silently excluding all untracked
files under cmd/domogeek/.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Hu8wwahgecuCGfesTKCfEd

vendor/golang.org/x/sys/unix/ioctl_zos.go

@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build zos && s390x
-// +build zos,s390x
 
 package unix
 
@@ -17,25 +16,23 @@ import (
 
 // IoctlSetInt performs an ioctl operation which sets an integer value
 // on fd, using the specified request number.
-func IoctlSetInt(fd int, req uint, value int) error {
+func IoctlSetInt(fd int, req int, value int) error {
 	return ioctl(fd, req, uintptr(value))
 }
 
 // IoctlSetWinsize performs an ioctl on fd with a *Winsize argument.
 //
 // To change fd's window size, the req argument should be TIOCSWINSZ.
-func IoctlSetWinsize(fd int, req uint, value *Winsize) error {
+func IoctlSetWinsize(fd int, req int, value *Winsize) error {
 	// TODO: if we get the chance, remove the req parameter and
 	// hardcode TIOCSWINSZ.
-	err := ioctl(fd, req, uintptr(unsafe.Pointer(value)))
-	runtime.KeepAlive(value)
-	return err
+	return ioctlPtr(fd, req, unsafe.Pointer(value))
 }
 
 // IoctlSetTermios performs an ioctl on fd with a *Termios.
 //
 // The req value is expected to be TCSETS, TCSETSW, or TCSETSF
-func IoctlSetTermios(fd int, req uint, value *Termios) error {
+func IoctlSetTermios(fd int, req int, value *Termios) error {
 	if (req != TCSETS) && (req != TCSETSW) && (req != TCSETSF) {
 		return ENOSYS
 	}
@@ -49,22 +46,22 @@ func IoctlSetTermios(fd int, req uint, value *Termios) error {
 //
 // A few ioctl requests use the return value as an output parameter;
 // for those, IoctlRetInt should be used instead of this function.
-func IoctlGetInt(fd int, req uint) (int, error) {
+func IoctlGetInt(fd int, req int) (int, error) {
 	var value int
-	err := ioctl(fd, req, uintptr(unsafe.Pointer(&value)))
+	err := ioctlPtr(fd, req, unsafe.Pointer(&value))
 	return value, err
 }
 
-func IoctlGetWinsize(fd int, req uint) (*Winsize, error) {
+func IoctlGetWinsize(fd int, req int) (*Winsize, error) {
 	var value Winsize
-	err := ioctl(fd, req, uintptr(unsafe.Pointer(&value)))
+	err := ioctlPtr(fd, req, unsafe.Pointer(&value))
 	return &value, err
 }
 
 // IoctlGetTermios performs an ioctl on fd with a *Termios.
 //
 // The req value is expected to be TCGETS
-func IoctlGetTermios(fd int, req uint) (*Termios, error) {
+func IoctlGetTermios(fd int, req int) (*Termios, error) {
 	var value Termios
 	if req != TCGETS {
 		return &value, ENOSYS