chore(vcs): switch repository to GitHEADmain

Add Git-specific repository configuration after migrating from
Mercurial.

Include a project-wide .gitignore for common development artifacts and a
commit message template documenting the Conventional Commits format.

1 files changed, 38 insertions, 0 deletions

diff --git a/.gitmessage b/.gitmessage
new file mode 100644
index 0000000..0504dbc
--- /dev/null
+++ b/.gitmessage
@@ -0,0 +1,38 @@
+
+# <type>[optional scope]: <short description>  (max 72 chars total) ------>|
+#
+# Types (choose ONE):
+#   feat      New feature (MINOR bump in SemVer)
+#   fix       Bug fix (PATCH bump)
+#   docs      Documentation only (README, man page, comments)
+#   style     Formatting, whitespace — no logic change
+#   refactor  Code restructure — no feature/fix
+#   perf      Performance improvement
+#   test      Tests only
+#   build     Build system / dependency changes
+#   ci        CI/CD configuration
+#   chore     Maintenance (release commits, tooling)
+#   revert    Revert a previous commit
+#
+# Breaking changes: append ! before the colon  →  feat(cli)!: ...
+# --------------------------------------------------------------------------
+
+# [blank line — required before body]
+
+# Body (optional): explain WHY, not WHAT. Wrap at 72 chars.            ---->|
+#
+# Motivation for the change, background, trade-offs considered, etc.
+# Use multiple paragraphs separated by blank lines if needed.
+
+# [blank line before footers]
+
+# Footers (optional):
+#   BREAKING CHANGE: <description of what breaks and how to migrate>
+#   Fixes: #<issue>
+#   Refs: #<issue>, <commit-sha>
+#   Reviewed-by: Name <email>
+#   Co-authored-by: Name <email>
+
+# SPDX-FileCopyrightText: 2026 Dennis Fink <me+coding@dennisfink.me>
+#
+# SPDX-License-Identifier: BSD-3-Clause