[build] add ValidateMembers xtask

[zimmy87]

This change adds a new xtask, ValidateMembers, that will check (and optionally fix) if any internal path dependency is missing from the workspace members in the repository's root ./Cargo.toml file.

[Copilot]

Pull request overview

Adds a new xtask subcommand (validate-members) intended to ensure all internal workspace path dependencies are also present in the root workspace members, and wires it into xtask precheck.

Changes:

• Introduce ValidateMembers xtask to validate (and optionally fix) missing workspace members.
• Run ValidateMembers as part of xtask precheck by default.
• Update root workspace members list and add toml_edit as a workspace dependency (and to xtask).

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
xtask/src/validate_members.rs	Implements the new ValidateMembers command (validate + optional fix).
xtask/src/precheck.rs	Adds a --validate-members stage and runs it by default.
xtask/src/main.rs	Registers the new ValidateMembers subcommand/module.
xtask/Cargo.toml	Adds toml_edit dependency for the new xtask.
Cargo.toml	Adds missing workspace members and introduces toml_edit to [workspace.dependencies].

[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated no new comments.