test: cover the account-name and hash guards

[retr0h]

Main's Go job fails at 99.8% against the 99.9% gate. Two merged security fixes added guard statements with no rejection tests. This restores the gate to 100.0%.

Provider (internal/provider/node/user):

• debian_user.go — invalid-name rows for GetUser, CreateUser, UpdateUser, DeleteUser
• debian_group.go — invalid-name rows for GetGroup, CreateGroup, UpdateGroup, DeleteGroup
• debian_ssh_key.go — invalid-username rows for ListKeys, AddKey, RemoveKey
• validatePasswordInput's name branch is unreachable through the API, because validateAccountName rejects colons and newlines first. Exposed through export_test.go and tested directly in a new validate_public_test.go.

In every provider row the setup sets no exec expectation, so gomock's strict controller fails if a command is ever invoked — that is the "no command ran" assertion, not just an error-string check.

Handlers (internal/controller/api/node/user): a 400 row for an invalid path name on all ten — user get/update/delete/password, group get/update/delete, and the three SSH-key operations. PutNodeUser and PutNodeGroup needed one more row each: their bodies carry Groups/Members tagged omitempty,dive,account_name, and the body-level rejection was untested and distinct from the path-parameter one.

internal/validation init: the account_name validator closure had never been exercised anywhere in the repository. It is now covered as a side effect of the handler rows, since validateName calls validation.Var(name, "required,account_name").

Hash error path: defaultHashPassword's error branch was unreachable, because the crypt library always succeeds with a nil salt. The library call now sits behind a generateHash package variable — the same injection convention hashPassword already uses — with a setter and reset in export_test.go and a row that injects a failure. Production wiring and hash format are unchanged.

Out of scope and untouched, since they predate this and were present when the gate passed: process/debian.go Processes, file_upload.go, the docker and power handlers, and agent/handler.go startInProgressKeepAlive.

Two commits rather than one: the second could not be amended into the first, and the history reads fine as a pair.

🤖 Generated with Claude Code

https://claude.ai/code/session_01FuKUsHFG1EqZXamffh9M2c

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@            Coverage Diff             @@
##             main     #514      +/-   ##
==========================================
- Coverage   99.93%   99.90%   -0.04%     
==========================================
  Files         488      489       +1     
  Lines       23108    23174      +66     
==========================================
+ Hits        23094    23153      +59     
- Misses         14       21       +7     

Files with missing lines	Coverage Δ
internal/controller/api/node/user/password_hash.go	100.00% <100.00%> (+25.00%)	⬆️

... and 1 file with indirect coverage changes

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