M10/D10: enable real-!testme path — fetch upstream tags + enroll 6 recipes in POLL_REPOS

fetch_recipe (SRC+REF/PR path) now read-only fetches published version tags from the public upstream
into the mirror clone, so the upgrade stage finds a previous published version (mirror PR branches
carry no tags → upgrade would skip). Guardrail-safe: only fetches tags, never pushes to the recipe
repo; plain git so the bot token isn't sent to upstream. Adds the 6 D10 recipes to the bridge
POLL_REPOS so !testme on their PRs triggers runs.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

modules/bridge.nix

@@ -40,7 +40,7 @@ let
           # admin-registered push optimization deduped against the poller (§4.1). Enrollment = add
           # the repo to POLL_REPOS (csv) + ensure tests/<recipe>/ exists.
           - POLL_INTERVAL=30
-          - POLL_REPOS=recipe-maintainers/cc-ci
+          - POLL_REPOS=recipe-maintainers/cc-ci,recipe-maintainers/custom-html,recipe-maintainers/keycloak,recipe-maintainers/cryptpad,recipe-maintainers/matrix-synapse,recipe-maintainers/lasuite-docs,recipe-maintainers/n8n
           - HMAC_FILE=/run/secrets/webhook_hmac
           - DRONE_TOKEN_FILE=/run/secrets/drone_token
           - GITEA_TOKEN_FILE=/run/secrets/gitea_token