Merge housekeeping updates via branch push instead of pull requests

Every dependency bump in the housekeeping list was already automerging,
but as a pull request - which meant an email and an open PR for every
bump even when it merged itself. Branch-push automerge makes green bumps
invisible; a failing one still surfaces as a pull request. The new
Matrix i18n workflow gates the i18n/requirements.txt ones with a real
exercise of the translation toolchain.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BhJbmhyUpt4qSrKD9cbJ5A

.github/renovate.json

@@ -45,8 +45,10 @@
 			"automergeType": "branch"
 		},
 		{
+			"description": "Housekeeping updates merge via branch push (no PR, no email); a failure on the branch still surfaces as a PR. i18n/requirements.txt bumps are exercised by the Matrix i18n workflow before merging.",
 			"matchFileNames": [
 				".github/workflows/close-stale-issues.yml",
+				".github/workflows/i18n.yml",
 				".github/workflows/lock-threads.yml",
 				".github/workflows/matrix.yml",
 				".github/workflows/update-translations.yml",
@@ -54,7 +56,8 @@
 				"i18n/requirements.txt",
 				"mise.toml"
 			],
-			"automerge": true
+			"automerge": true,
+			"automergeType": "branch"
 		}
 	],
 	"pre-commit": {