Add bats test suite for git-manager and obsidian-vault-kb

Isolated per-test $HOME sandboxing via tests/helpers/common.bash.
Covers both plugins' wrapper scripts, their setup.sh, and
git-manager's two PreToolUse hooks (53 tests). Verified the suite
catches regressions by temporarily reintroducing the recently-fixed
vault_search.sh -g/-- ordering bug and confirming it fails.

tests/README.md

@@ -0,0 +1,39 @@
+# Tests
+
+A [bats-core](https://bats-core.readthedocs.io/) suite covering both
+plugins' wrapper scripts, their `setup.sh`, and git-manager's two
+`PreToolUse` hooks. Plain bats assertions only (`run` + `[ ]`/`[[ ]]`) — no
+extra helper libraries.
+
+## Install
+
+```bash
+sudo apt install bats
+```
+
+## Run
+
+```bash
+bats -r tests/                       # everything (-r: recurse into subdirs)
+bats -r tests/git-manager/           # one plugin
+bats tests/obsidian-vault-kb/vault_search.bats   # one file
+```
+
+## How it's isolated
+
+Every test points `$HOME` at a fresh, bats-managed `$BATS_TEST_TMPDIR/home`
+(see `tests/helpers/common.bash`, `sandbox_home`) before running any script
+under test. Since every script here resolves its config from
+`~/.agent-skills/<name>/config.json` and setup.sh writes to
+`~/.claude/settings.json`, this means:
+
+- Tests never read or write your real `~/.agent-skills/` or
+  `~/.claude/settings.json`.
+- Nothing needs manual cleanup — bats deletes `$BATS_TEST_TMPDIR` after
+  each test automatically.
+- Tests that exercise a `setup.sh` run the real script end to end (it's
+  what deploys the stable script copies + writes permissions/config), not a
+  mocked version.
+
+There's no CI wiring for this suite yet — run it manually before/after
+touching anything under `skills/` or `vendor/claude-code/plugins/`.