Skip password prompt during wallet creation when FULMINE_UNLOCKER_PASSWORD and FULMINE_UNLOCKER_TYPE are set

[arkanaai]

Summary

When FULMINE_UNLOCKER_PASSWORD and FULMINE_UNLOCKER_TYPE environment variables are set, the user should not be prompted for a password during wallet creation — the env vars already provide that information.

Current Behavior

The wallet creation flow (via gRPC CreateWallet / HTTP POST /v1/wallet/create) requires the caller to supply a password field in CreateWalletRequest. This is validated in internal/interface/grpc/handlers/utils.go by parsePassword(), which returns "missing password" if the field is empty — even if the operator has already configured FULMINE_UNLOCKER_PASSWORD via the environment.

Expected Behavior

If both FULMINE_UNLOCKER_PASSWORD and FULMINE_UNLOCKER_TYPE (set to "env") are configured, CreateWallet should:

1. Accept an empty password field in the request
2. Fall back to calling unlockerSvc.GetPassword(ctx) to retrieve the password from the configured unlocker
3. Proceed with wallet setup using that password — no interactive prompt needed

This mirrors how autoUnlock in internal/interface/grpc/service.go (line 325) already uses the unlocker to unlock after startup.

Why

This improves the automated/headless deployment experience. Operators running fulmine in Docker with env vars already know the password — requiring it again on first run forces an interactive fulmine createwallet call or scripted API call with the password in plaintext, defeating the purpose of the unlocker abstraction.

Affected Components

File	Relevance
internal/interface/grpc/handlers/wallet_handler.go	CreateWallet handler — calls parsePassword(req.GetPassword()) unconditionally
internal/interface/grpc/handlers/utils.go	parsePassword() — rejects empty password (line 33–41)
internal/interface/grpc/service.go	Has access to unlockerSvc — already uses it for autoUnlock
internal/core/application/service.go	Setup() — the function that actually initializes the wallet with the password
internal/config/config.go	FULMINE_UNLOCKER_PASSWORD, FULMINE_UNLOCKER_TYPE env vars (lines 88–90); initUnlockerService()
internal/infrastructure/unlocker/env/service.go	envunlocker.NewService — returns password from env
internal/core/ports/unlocker.go	Unlocker interface — GetPassword(ctx)

Suggested Approach

Option A — handle in WalletHandler: Pass the unlockerSvc into the wallet handler and modify CreateWallet to call unlockerSvc.GetPassword(ctx) if req.GetPassword() is empty and an unlocker is configured.

Option B — handle in gRPC service.go: After svc.Start(), check if the wallet is uninitialized and an unlocker is configured. If so, auto-create the wallet is out of scope — but the service could expose a helper that allows CreateWallet with an empty password field to use the unlocker (similar to the autoUnlock pattern).

Option A is simpler and keeps the change local to the wallet handler.

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Requested by kukks via Slack #fulmine