Derive analysis root from config path

[longlho]

Summary:

• Use the parent directory of --config as the analysis root when --directory is omitted.
• Preserve the logical analysis root instead of canonicalizing it out of runfiles.
• Apply the same config-parent default through the Node/NAPI wrapper.
• Add CLI and npm smoke coverage for config-only runs.

Verification:

• bazel test //crates/codescythe:codescythe_test //crates/codescythe_cli:codescythe_cli_test
• bazel build //crates/codescythe_cli:codescythe //crates/codescythe_napi:codescythe_napi //packages/codescythe-darwin-arm64:package
• CODESCYTHE_PACKAGE_DIR=/private/tmp/... CODESCYTHE_NATIVE_PACKAGE_DIR=/private/tmp/... pnpm test:npm
• Manual CLI fixture: running from /private/tmp with only --config finds the fixture dead code

Note:

• Local bazel test //... is blocked by an untracked .worktrees/ checkout under this repo, which Bazel descends into. CI should not have that local directory.