bug: missing-tool and missing-data have surprising create-issue behavior depending on implicit vs explicit enablement

[eaftan]

Bug Report

Both missing-tool and missing-data have surprising create-issue behavior: an empty config block silently enables issue creation, while not mentioning the key at all leaves it disabled. These should behave the same way.

Current behavior

Both missing-tool and missing-data have three distinct behaviors:

Configuration	create-issue value
Not mentioned at all	false (auto-enabled, reports only)
missing-tool: / missing-data: (explicit, nil value)	true (creates issues)
missing-tool: false / missing-data: false	Fully disabled

The gap between rows 1 and 2 is unintuitive. Writing missing-tool: or missing-data: with no value looks like "I acknowledge the default" but actually changes behavior by enabling issue creation.

Expected behavior

An empty missing-tool: or missing-data: block should behave identically to not mentioning the key at all. Users who want issue creation should explicitly opt in with create-issue: true.

Root cause

Both types share parseIssueReportingConfig (pkg/workflow/missing_issue_reporting.go), which sets CreateIssue: true when the key is present with a nil value (lines 37-42):

// Enabled with no value: missing-data: (nil)
if configData == nil {
    cfg.CreateIssue = true  // <-- surprising default
    cfg.TitlePrefix = defaultTitle
    cfg.Labels = []string{}
    return cfg
}

But the auto-enable path in pkg/workflow/safe_outputs_config.go (lines 302-332) explicitly sets CreateIssue: false:

// missing-tool (lines 307-315)
if _, exists := outputMap["missing-tool"]; !exists {
    config.MissingTool = &MissingToolConfig{
        CreateIssue: false,
    }
}

// missing-data (lines 323-331) — identical pattern
if _, exists := outputMap["missing-data"]; !exists {
    config.MissingData = &MissingDataConfig{
        CreateIssue: false,
    }
}

Suggested fix

Change parseIssueReportingConfig so that the nil-value case sets CreateIssue: false, matching the auto-enable behavior. This makes the empty-block and not-mentioned cases consistent.