Release 2.0.0 — explicit monorepo_url, drop first-target-host inference

Breaking change. The monorepo's gitea host was previously inferred from the
first target's subrepo_url, silently coupling the two and breaking on any
multi-host setup (monorepo on host A, target on host B). v2.0.0 replaces the
inference with a required josh.monorepo_url field that mirrors subrepo_url —
same parsing, same SSH/HTTPS auth options, same shape.

- schema_version: 2 is now required; v1 configs are rejected with a clear migration error
- josh.monorepo_url is required; josh.monorepo_auth is optional (default https)
- mono_auth_url() in lib/auth.sh mirrors subrepo_auth_url()
- MONOREPO_API derives from monorepo_url's host instead of .[0].gitea_host;
  env-var override preserved as escape hatch
- initial_import() and force-push call mono_auth_url() instead of building URLs inline
- ADR-012 documents the rationale; CHANGELOG includes migration snippet

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

lib/auth.sh

@@ -2,7 +2,8 @@
 # lib/auth.sh — Authenticated URLs, remote queries, and PR creation
 #
 # Requires: lib/core.sh and lib/config.sh sourced first
-# Expects: JOSH_PROXY_URL, MONOREPO_PATH, BOT_USER, GITEA_TOKEN, JOSH_FILTER,
+# Expects: JOSH_PROXY_URL, MONOREPO_PATH, MONOREPO_URL, MONOREPO_AUTH,
+#           BOT_USER, GITEA_TOKEN, JOSH_FILTER,
 #           SUBREPO_URL, SUBREPO_AUTH, SUBREPO_TOKEN (set by parse_config + load_target)
 
 # ─── Josh-Proxy Auth URL ───────────────────────────────────────────
@@ -29,13 +30,24 @@ subrepo_auth_url() {
 }
 
 # ─── Monorepo Auth URL ─────────────────────────────────────────────
-# Derives a push-capable HTTPS URL from MONOREPO_API.
-# MONOREPO_API shape: https://<host>/api/v1/repos/<org/repo>
+# HTTPS: injects user:token into MONOREPO_URL (auto-converts git@ form to https)
+# SSH:   returns bare MONOREPO_URL (auth via user's ssh-agent / ~/.ssh/config,
+#        or via GIT_SSH_COMMAND if the caller wired one up for the monorepo host)
 
 mono_auth_url() {
-  local api_host_path
-  api_host_path=$(echo "$MONOREPO_API" | sed 's|https://||; s|/api/v1/repos/|/|')
-  echo "https://${BOT_USER}:${GITEA_TOKEN}@${api_host_path}.git"
+  if [ "${MONOREPO_AUTH:-https}" = "ssh" ]; then
+    echo "$MONOREPO_URL"
+  else
+    local https_url="$MONOREPO_URL"
+    # Convert git@host:org/repo.git → https://host/org/repo.git so token injection works
+    if [[ "$https_url" == git@* ]]; then
+      https_url=$(echo "$https_url" | sed -E 's|^git@([^:]+):(.+)$|https://\1/\2|')
+    elif [[ "$https_url" == ssh://* ]]; then
+      https_url=$(echo "$https_url" | sed -E 's|^ssh://[^@]*@([^/]+)/(.+)$|https://\1/\2|')
+    fi
+    # shellcheck disable=SC2001
+    echo "$https_url" | sed "s|https://|https://${BOT_USER}:${GITEA_TOKEN}@|"
+  fi
 }
 
 # ─── Remote Queries ─────────────────────────────────────────────────