test: fix bun PATH in subprocess tests and set -eo pipefail in shell scripts (#1353)

Fixes 256 failing tests that spawn bun subprocesses. These tests were
failing because bun was not in the child process PATH. Ensures all
CLI test helpers pass PATH with $HOME/.bun/bin included.

Also corrects two gptme.sh scripts to use 'set -eo pipefail' instead
of bare 'set -e' for proper error handling, per shellcheck conventions.

Changes:
- 7 CLI test files: add PATH=$HOME/.bun/bin to execSync/spawnSync env
- 2 shell scripts: use set -eo pipefail for proper error handling

Results: 256 tests now passing, 0 failures in subprocess CLI tests.

Co-authored-by: test-engineer <agent@spawn.local>
Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

cli/src/__tests__/cli-version-and-dispatch.test.ts

@@ -40,6 +40,8 @@ function runCLI(
     timeout: 15000,
     env: {
       ...process.env,
+      // Ensure bun is in PATH for child processes
+      PATH: `${process.env.HOME}/.bun/bin:${process.env.PATH}`,
       SPAWN_NO_UPDATE_CHECK: "1",
       BUN_ENV: "test",
       // Avoid terminal-dependent output