feat(git): user-level hooks auto-dispatch into <repo>/.githooks/

Inverts the hook delegation model. Previously per-repo hooks required
a project to either (a) write the entire hook themselves and lose the
global signed-commit / agent-author gate, or (b) override
core.hooksPath and write passthrough stubs that exec back to
$HOME/.config/git/hooks/*. Both are ergonomically miserable.

Now: the global hooks at ~/.config/git/hooks/ are *always* the entry
point. Each one calls a shared dispatcher (_dispatch.sh) that runs
<repo>/.githooks/<hookname> if it exists, propagating its exit status,
and then continues with whatever the global hook itself wants to do.
Projects just drop an executable file at .githooks/<name> — no
core.hooksPath, no stubs, no boilerplate. Repos that don't have a
.githooks/ dir keep working exactly as before.

GIT_HOOK_DISPATCHED guards against re-entry so legacy repos using the
old stub-and-exec pattern don't loop. pre-push tees stdin so both the
repo hook and the global ref-list loop see the full push payload.

Adds two new always-no-op global hooks (pre-commit, post-commit)
purely so the dispatch happens for those events too — previously only
commit-msg and pre-push existed globally.

Refactors this dotfiles repo to use the new pattern: drops the
self-delegating .githooks/pre-push stub and removes the per-repo
core.hooksPath override from `just init` (now an idempotent unsetter
to clean up the override from past bootstraps). The remote-dev VM's
home-manager profile symlinks all four hooks plus _dispatch.sh.

1 files changed, 14 insertions, 0 deletions

diff --git a/dot_config/git/hooks/executable_post-commit b/dot_config/git/hooks/executable_post-commit
new file mode 100755
index 0000000..45f13f0
--- /dev/null
+++ b/dot_config/git/hooks/executable_post-commit
@@ -0,0 +1,14 @@
+#!/bin/sh
+# User-level post-commit. No global checks — exists purely so that
+# `<repo>/.githooks/post-commit` gets picked up automatically without
+# the project needing to override core.hooksPath. If there is no
+# per-repo hook this is a no-op. post-commit's exit status is ignored
+# by git, but we still propagate it for clarity.
+
+set -eu
+
+# shellcheck source=./_dispatch.sh
+. "${0%/*}/_dispatch.sh"
+dispatch_repo_hook post-commit "$@"
+
+exit 0