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

go.mod

@@ -1,11 +1,12 @@
 module domogeek
 
-go 1.18
+go 1.25.0
 
 require (
 	github.com/avast/retry-go v2.7.0+incompatible
 	github.com/dolanor/caldav-go v0.2.1
 	github.com/hellofresh/health-go/v4 v4.5.0
+	github.com/modelcontextprotocol/go-sdk v1.7.0
 	github.com/prometheus/client_golang v1.12.1
 	go.uber.org/zap v1.21.0
 )
@@ -14,14 +15,21 @@ require (
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cespare/xxhash/v2 v2.1.2 // indirect
 	github.com/golang/protobuf v1.5.2 // indirect
+	github.com/google/jsonschema-go v0.4.3 // indirect
 	github.com/matttproud/golang_protobuf_extensions v1.0.1 // indirect
 	github.com/prometheus/client_model v0.2.0 // indirect
 	github.com/prometheus/common v0.32.1 // indirect
 	github.com/prometheus/procfs v0.7.3 // indirect
+	github.com/segmentio/asm v1.1.3 // indirect
+	github.com/segmentio/encoding v0.5.4 // indirect
+	github.com/yosida95/uritemplate/v3 v3.0.2 // indirect
 	go.opentelemetry.io/otel v1.0.0 // indirect
 	go.opentelemetry.io/otel/trace v1.0.0 // indirect
 	go.uber.org/atomic v1.7.0 // indirect
 	go.uber.org/multierr v1.6.0 // indirect
-	golang.org/x/sys v0.0.0-20220114195835-da31bd327af9 // indirect
+	golang.org/x/oauth2 v0.35.0 // indirect
+	golang.org/x/sync v0.20.0 // indirect
+	golang.org/x/sys v0.41.0 // indirect
+	golang.org/x/time v0.15.0 // indirect
 	google.golang.org/protobuf v1.26.0 // indirect
 )