Support pre-dispatch hook registration in app! #434

Description

Core pre-dispatch hooks landed in PR #403, but app! still accepts only state and owns_logging keyword arguments; crates/edgezero-macros/src/app.rs:33. Application authors must reconstruct the generated router to install a hook while retaining routes, middleware, state, manifest/store/logging metadata and app identity.

Steps to reproduce

Attempt to register a pre-dispatch hook using app! keyword syntax. The parser rejects an unknown argument. Compare the manual workaround/tests from #403 and enumerate every generated surface the replacement must preserve.

Expected behavior

An optional documented app! hook argument installs the existing pre-dispatch hook while preserving generated behavior and legacy invocation syntax.

Impact

Manual reconstruction repeats routing/metadata configuration and is easy to drift when generated application surfaces change.

Proposed fix

Extend only app! argument parsing and builder generation using the existing hook registration contract. Specify value/Arc and duplicate registration behavior, and test continuation/terminal paths plus preservation of generated surfaces. No runtime-specific dependency belongs in core/macros.

Done when

• Define and document an optional macro argument for hook installation, including value/Arc behavior and duplicate-registration semantics.
• Existing macro syntax and generated application behavior remain compatible.
• Tests demonstrate terminal and continuation behavior and preservation of every generated metadata/router surface.
• No runtime-specific dependencies enter core or macros.

Related

• Follow-up to merged PR Add pre-dispatch hooks and explicit request ingress fidelity #403.
• Current core hook behavior remains the authoritative lifecycle contract. No open PR in the reviewed inventory implements this macro extension.