Add the GitHub and Gitea steps and split the script into library files

Dry run by default: the script reads from both hosts (tokens, owners,
names, license, SSH) and prints a plan; --apply creates the repositories
and the Gitea -> GitHub push mirror after a final yes. Choosing GitHub
applies the AGPL-3.0 license to the Gitea repository. A failed step is
reported with what exists and how to continue; nothing is ever deleted.

create-project.sh is now the entry point; the work lives in src/lib/, one
responsibility per file. .gitignore gets !src/lib (the Python template
ignores any lib/ folder). Tests grow to 599 checks, with a stub curl and
ssh, and guards for the file structure.

Task: MIL-002#1
Task: MIL-002#2
Task: MIL-002#3
Task: MIL-002#4
Task: MIL-002#5
Task: MIL-002#6
Refs #9
Refs #10
Refs #11
Refs #12
Refs #13
Refs #14

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/lib/repositories.sh

@@ -0,0 +1,47 @@
+# shellcheck shell=bash
+# shellcheck disable=SC2004,SC2034,SC2154  # shared state and arrays are declared in constants.sh
+# repositories.sh - Creating the GitHub and Gitea repositories.
+#
+# Part of create-project.sh: sourced by it, never run on its own.
+#
+# Provides: repo_body, create_repository
+
+# repo_body HOST: the JSON body that creates the repository on HOST.
+repo_body() {
+  local host="$1" description private=true extra=""
+  description="$(json_escape "${PROJECT[description]}")"
+  if [[ ${PROJECT[visibility]} != private ]]; then
+    private=false
+  fi
+  if [[ $host == github ]]; then
+    printf '{"name":"%s","description":"%s","private":%s,"auto_init":false}' \
+      "${PROJECT[name]}" "$description" "$private"
+    return 0
+  fi
+  if ((PROJECT[has_github])); then
+    extra=',"auto_init":true,"license":"'"$AGPL_LICENSE_KEY"'"'
+  else
+    extra=',"auto_init":false'
+  fi
+  printf '{"name":"%s","description":"%s","private":%s,"default_branch":"%s"%s}' \
+    "${PROJECT[name]}" "$description" "$private" "$DEFAULT_BRANCH" "$extra"
+}
+
+# create_repository HOST: create the repository, or reuse the existing one.
+create_repository() {
+  local host="$1" label owner path
+  label="$(host_label "$host") repository"
+  owner="$(repo_owner "$host")"
+  if is_reused "$host"; then
+    finish_step "$label" "reused" "$(repo_url "$host")"
+    return 0
+  fi
+  begin_step "$label"
+  path="/user/repos"
+  if [[ ${STATE[${host}_owner_kind]} == organization ]]; then
+    path="/orgs/$owner/repos"
+  fi
+  api_call "$host" POST "$path" "$(repo_body "$host")"
+  expect_status "cannot create the $label" 201
+  finish_step "$label" "created" "$(repo_url "$host")"
+}