gitehr initialise

Aliases: init, initialize

gitehr init

Initialises a new GitEHR repository in the current working directory. Behaviour (see src/commands/init.rs): 1. Fails if .gitehr already exists to avoid overwriting an existing record. 2. Copies the template structure (including journal, state, imaging, and README files) from gitehr-folder-structure into the working directory; creates .gitehr locally. 3. Generates a 32-byte random seed, hashes it with SHA-256, and writes a genesis journal entry whose parent_hash references that seed to anchor the chain. 4. Prints confirmation: “Initialized empty GitEHR repository.”