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/github.com/segmentio/asm/cpu/cpu.go

@@ -0,0 +1,22 @@
+// Pakage cpu provides APIs to detect CPU features available at runtime.
+package cpu
+
+import (
+	"github.com/segmentio/asm/cpu/arm"
+	"github.com/segmentio/asm/cpu/arm64"
+	"github.com/segmentio/asm/cpu/x86"
+)
+
+var (
+	// X86 is the bitset representing the set of the x86 instruction sets are
+	// supported by the CPU.
+	X86 = x86.ABI()
+
+	// ARM is the bitset representing which parts of the arm instruction sets
+	// are supported by the CPU.
+	ARM = arm.ABI()
+
+	// ARM64 is the bitset representing which parts of the arm64 instruction
+	// sets are supported by the CPU.
+	ARM64 = arm64.ABI()
+)