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/yosida95/uritemplate/v3/README.rst

@@ -0,0 +1,46 @@
+uritemplate
+===========
+
+`uritemplate`_ is a Go implementation of `URI Template`_ [RFC6570] with
+full functionality of URI Template Level 4.
+
+uritemplate can also generate a regexp that matches expansion of the
+URI Template from a URI Template.
+
+Getting Started
+---------------
+
+Installation
+~~~~~~~~~~~~
+
+.. code-block:: sh
+
+   $ go get -u github.com/yosida95/uritemplate/v3
+
+Documentation
+~~~~~~~~~~~~~
+
+The documentation is available on GoDoc_.
+
+Examples
+--------
+
+See `examples on GoDoc`_.
+
+License
+-------
+
+`uritemplate`_ is distributed under the BSD 3-Clause license.
+PLEASE READ ./LICENSE carefully and follow its clauses to use this software.
+
+Author
+------
+
+yosida95_
+
+
+.. _`URI Template`: https://tools.ietf.org/html/rfc6570
+.. _Godoc: https://godoc.org/github.com/yosida95/uritemplate
+.. _`examples on GoDoc`: https://godoc.org/github.com/yosida95/uritemplate#pkg-examples
+.. _yosida95: https://yosida95.com/
+.. _uritemplate: https://github.com/yosida95/uritemplate