feat(cli): support user-defined templates for --init

[lazizbekravshanov]

Description

Adds support for user-defined --init templates, alongside the existing built-in templates:

• --templates-dir <PATH> (env: GIT_CLIFF_TEMPLATES_DIR) — a directory of user .toml templates that --init <name> can use. A user template overrides a built-in template of the same name.
• --list-templates — prints all available template names (built-in + user-defined), one per line, sorted and deduplicated. This covers the completion use case from the issue.

Behavior details:

• Existing --init behavior is unchanged when no --templates-dir is given.
• A missing or non-directory --templates-dir is a clear error naming the offending path; non-.toml files in the directory are ignored.
• --list-templates prints and exits (like --init), and works outside a git repository.
• Tera body-templates (--body / --template) are unaffected — this only concerns the --init config presets.

Motivation and Context

Closes #412. Users who keep their own --init template presets currently can't use them through git-cliff's built-in mechanism, and there was no way to enumerate the available templates (needed for shell/editor completion).

How Has This Been Tested?

• Unit tests (test-first / TDD):
  • git-cliff-core (embed.rs): built-in listing (sorted, no extension); merging a user directory (ignoring non-.toml, deduped); user template overriding a built-in; .toml extension normalization; and a clear error when the directory is missing.
  • git-cliff (args.rs, lib.rs): parsing --templates-dir / --list-templates; init_config writing the user template (and falling back to the built-in).
• cargo test (workspace): all green.
• cargo +nightly fmt --all -- --check: clean.
• cargo clippy --tests -- -D warnings: clean on the changed code. (Note: on my local toolchain — rustc 1.97.0 — clippy also reports one pre-existing useless_borrows_in_formatting lint in git-cliff-core/src/repo.rs, which is unrelated to this change and outside the diff.)
• Manual end-to-end on the built binary: listing built-ins; merging + overriding via --templates-dir; the GIT_CLIFF_TEMPLATES_DIR env var; --init <name> --templates-dir writing user content; the missing-directory error; and confirming both commands work outside a git repository.

Types of Changes

• New feature (non-breaking change which adds functionality)
• Documentation (no code change)

Checklist:

• My code follows the code style of this project.
• I have updated the documentation accordingly (if applicable).
• I have formatted the code with rustfmt.
  • cargo +nightly fmt --all
• I checked the lints with clippy.
  • cargo clippy --tests --verbose -- -D warnings
• I have added tests to cover my changes.
• All new and existing tests passed.
  • cargo test

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[lazizbekravshanov]

Quick heads-up on the red "Test suite" check: the failure is in the Codecov upload step, not the tests. The uploader couldn't verify its own GPG signature (gpg: Can't check signature: No public key → "Could not verify signature"), which looks like a transient Codecov/keyserver issue — the test job itself passes and the other checks are green. A re-run should clear it whenever convenient. Happy to adjust anything on my end if needed!

[lazizbekravshanov]

Hi @orhun — gentle nudge on this one whenever you have a moment 🙂 It implements #412 (which you'd approved): --templates-dir <PATH> + GIT_CLIFF_TEMPLATES_DIR, --list-templates, and user templates overriding the built-ins, all TDD'd (10 unit tests + behavioural coverage). The branch is still MERGEABLE and rebased on main.

Just to re-flag: the one red "Test suite" check is the Codecov upload step failing to verify its own GPG signature (a transient uploader/keyserver issue), not the tests — the actual test job and the other 107 checks are green. Happy to rebase, adjust the flag/UX, or split anything out if that helps review. No rush at all, and thanks for your time!

[lazizbekravshanov]

Hi @orhun, following up on this one. It implements #412 (user-defined templates for --init): the --templates-dir <PATH> flag, the GIT_CLIFF_TEMPLATES_DIR env var, and --list-templates, with user templates overriding the built-ins. Tests, clippy, and fmt are green (the one red check is the codecov upload step, an infra flake that also fails on main). Happy to rebase or adjust anything whenever you get a chance to look.

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[lazizbekravshanov]

Closing this to clear my queue. The branch stays on my fork, so if you would still like the templates feature I am glad to reopen and rebase it whenever.