fix(devnet): only show init hint for InitializationError

[RetricSu]

Fixes #406

Problem

`offckb devnet config` was showing the "run `offckb node` once to initialize devnet config files first" hint for ALL errors, including user input errors like invalid `--set` syntax or validation failures. This was misleading.

Solution

• Added `InitializationError` class to distinguish initialization errors from user input errors
• Only show the init hint when catching `InitializationError` (missing config path, ckb.toml, or miner.toml)
• Added type safety guard for error handling

Changes

1. `src/devnet/config-editor.ts`: Added `InitializationError` class
2. `src/devnet/config-editor.ts`: Updated throws to use `InitializationError` for missing files/paths
3. `src/cmd/devnet-config.ts`: Updated catch block to conditionally show hint
4. `tests/devnet-config-command.test.ts`: Added 6 unit tests for error classification

Testing

• All 8 tests pass (2 existing + 6 new)
• Verified: parse errors, validation errors → NO hint
• Verified: missing config files → WITH hint

[github-actions]

✅ Changeset file detected.

[Copilot]

Pull request overview

This PR refines offckb devnet config error handling so the “run offckb node once…” initialization hint is only shown for true devnet initialization failures, instead of for all errors (including user input/validation issues).

Changes:

• Introduces InitializationError in the devnet config editor and throws it for missing config path / missing required TOML files.
• Updates devnetConfig to conditionally print the initialization hint only when catching InitializationError, while improving catch type-safety.
• Adds unit tests to verify hint behavior across parse errors, validation/unknown-field errors, and initialization errors.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
src/devnet/config-editor.ts	Adds InitializationError and uses it for missing path/config-file checks.
src/cmd/devnet-config.ts	Prints the initialization hint only for InitializationError; safer error-to-message handling.
tests/devnet-config-command.test.ts	Adds tests ensuring the hint is suppressed for non-init errors and shown for init errors.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.