Search parent directories for the application manifest #126

Description

Resolve edgezero.toml from parent directories when local development commands run inside a project subdirectory.

A reusable find_manifest_upwards helper exists, and Axum uses it for adapter host/port configuration. Generic CLI loading still resolves only EDGEZERO_MANIFEST or ./edgezero.toml; missing defaults silently produce no application manifest. The command on main is serve, not dev.

Steps to reproduce

1. Inspect generic CLI load_manifest_optional and the existing upward-search helper.
2. Compare running serve from the project root with resolving its application manifest from a nested directory.

Expected behavior

The local-development command finds the nearest applicable project manifest while preserving explicit manifest overrides and manifest-relative paths.

Impact

Nested invocation can silently lose generic adapter/store configuration even when adapter-specific discovery finds a parent file.

Proposed fix

Reuse upward discovery in the generic application-manifest path, define its project boundary, and preserve explicit missing-manifest errors.

Done when

• Nested invocation finds the intended nearest parent edgezero.toml.
• Explicit EDGEZERO_MANIFEST paths keep precedence and fail clearly when invalid.
• Resolved paths remain relative to the chosen manifest/project root.
• Tests cover nested projects, no-manifest behavior and explicit override precedence.

Related

• Parent: Complete CLI and local developer workflows #124.
• Generic CLI manifest loading
• Upward manifest-search helper
• Existing Axum parent lookup