docs(v0.4.1): add nested git guidance for project mode

Project CLAUDE.md template now includes a Git section stating that the
workspace uses a single git repo at the root and subdirectory git init
is not permitted. docs/commands.md picks up the same guidance under the
--project flag section.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/commands.md

@@ -54,6 +54,12 @@ When `--no-launch` is used, no session is started and no session log is written.
 - `CTASK_PROJECT_ROOT` set, no `-c`: workspace goes directly under `$CTASK_PROJECT_ROOT/<date>_<slug>` (no `projects/` subdirectory is appended)
 - `CTASK_PROJECT_ROOT` set, explicit `-c <category>`: workspace goes under `$CTASK_PROJECT_ROOT/<category>/<date>_<slug>`
 
+**Single git repo rule:**
+
+Project workspaces use a single git repository initialized at the workspace root.
+Do not create nested git repositories inside the workspace. If your project code
+lives in a subdirectory, it is tracked by the root repo.
+
 ### Seed directories
 
 On `ctask new`, after writing the built-in defaults, ctask copies the contents of an optional user seed directory into the workspace. Files in the seed directory overwrite the built-in defaults; subdirectories are preserved recursively. `task.yaml` and `.ctask/` at the seed root are always skipped.

internal/seed/templates.go

@@ -62,6 +62,12 @@ This is a ctask project workspace -- a long-lived working environment, not a dis
 - Record important assumptions and actions in notes.md.
 - Keep the workspace root clean.
 
+## Git
+
+This workspace uses a single git repository at the workspace root.
+Do not initialize additional git repositories inside subdirectories.
+All project code, even if nested in a subdirectory, is tracked by the root repo.
+
 ## Session Handoff
 
 Before ending a session, append a brief summary to notes.md with:

internal/seed/templates_test.go

@@ -62,6 +62,18 @@ func TestClaudeMDProjectContainsRequiredSections(t *testing.T) {
 	}
 }
 
+func TestClaudeMDProjectContainsNestedGitRule(t *testing.T) {
+	body := ClaudeMDProject()
+	for _, must := range []string{
+		"single git repository",
+		"Do not initialize additional git repositories",
+	} {
+		if !strings.Contains(body, must) {
+			t.Errorf("ClaudeMDProject missing guidance %q", must)
+		}
+	}
+}
+
 func TestNotesMDIsASCII(t *testing.T) {
 	content := NotesMD("test title")
 	for i, b := range []byte(content) {