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/tools.sh

@@ -0,0 +1,26 @@
+# shellcheck shell=bash
+# shellcheck disable=SC2004,SC2034,SC2154  # shared state and arrays are declared in constants.sh
+# tools.sh - Checking that the required tools are installed.
+#
+# Part of create-project.sh: sourced by it, never run on its own.
+#
+# Provides: check_tools
+
+check_tools() {
+  local tool
+  local missing=()
+  for tool in git curl mktemp; do
+    if ! command -v "$tool" >/dev/null 2>&1; then
+      missing+=("$tool")
+    fi
+  done
+  if ((${#missing[@]} > 0)); then
+    die "required tool(s) not found: ${missing[*]}. Install them and try again."
+  fi
+  if command -v jq >/dev/null 2>&1; then
+    HAS_JQ=1
+  else
+    HAS_JQ=0
+    warn "jq not found; using the built-in JSON reader (install jq for stricter parsing)"
+  fi
+}