fix: list supported methods in unknown method errors

[srpatcha]

Summary

Fixes #2712

The consolidated method-dispatch tools returned a bare unknown method: <value> without listing valid methods, unlike labels.go which already says Supported methods are: create, update, delete. This makes the behavior inconsistent and unhelpful for callers.

Changes

Appended the list of supported methods to every unknown method error across the method-dispatch tools:

File	Tool(s)
issues.go	issue_read, sub-issue write
issue_dependencies.go	sub-issue read / write
ui_tools.go	ui_get
pullrequests.go	pull_request_read, pull_request_review_write
projects.go	projects list / get / write
actions.go	actions list / get / run

Additionally, pull_request_review_write used mapstructure.WeakDecode and did not validate that method was provided, so omitting it produced a confusing unknown method: (empty value) — which reads like a routing bug rather than a missing argument. Added an explicit check:

if params.Method == "" {
    return utils.NewToolResultError("missing required parameter: method. Supported methods are: create, submit_pending, delete_pending, resolve_thread, unresolve_thread"), nil, nil
}

Testing

All existing tests that assert on unknown method use assert.Contains, so the appended text preserves the existing substring matches — no test changes required. The new error messages are strict supersets of the previous ones.