Add the RepoFoundry foundation: config parsing, HTTP helper, prompts, tests

create-project.sh validates config.env and .env (parsed, never sourced),
checks the required tools, asks for the project details and prints a
summary. It makes no network call and no change on disk yet.

- config.env.example and .env.example hold placeholders only
- tokens go through a private curl config file, never the command line
- tests run in private directories with a stub curl; shellcheck and shfmt
  are part of tests/run-tests.sh

Task: MIL-001#1
Task: MIL-001#2
Task: MIL-001#3
Task: MIL-001#4
Task: MIL-001#5
Task: MIL-001#6
Closes #3
Closes #4
Closes #5
Closes #6
Closes #7
Closes #8

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

.env.example

@@ -0,0 +1,22 @@
+# RepoFoundry credentials. Placeholders only: never put a real value in this
+# file or commit one.
+#
+# Copy this file to .env, fill in the values and keep it private
+# (chmod 600 .env on Linux and macOS). .env is ignored by git. The file is
+# read as plain KEY=VALUE lines and never executed. Values may be wrapped in
+# single or double quotes.
+
+# GitHub personal access token. Needed only when you choose to create a
+# GitHub repository. It creates the repository and is also the password of the
+# Gitea push mirror, so it needs permission to create repositories for the
+# chosen owner and to push to the new one. Prefer a fine-grained token.
+GITHUB_PAT=
+
+# GitHub account the token belongs to. It identifies who authenticates; it is
+# only a default suggestion for the owner prompt, because the repository can
+# belong to an organization.
+GITHUB_USER=
+
+# Gitea access token (required). It needs permission to create repositories
+# for the chosen owner and to manage the repository's push mirror.
+GITEA_TOKEN=