Add workflow inventory package for unified name extraction and file discovery

[Copilot]

Workflow name extraction and normalization logic was scattered across pkg/cli/workflows.go, pkg/cli/status_command.go, and inline throughout the codebase with variations in handling edge cases.

Changes

New package: pkg/cli/inventory

• ExtractWorkflowName(path) - Normalizes workflow names from paths, handling .md, .lock.yml, .campaign.md, .campaign.lock.yml, .campaign.g.md
• NormalizeWorkflowName(input) - Semantic alias for user input normalization
• GetWorkflowPath(name, dir) - Converts workflow name to markdown file path
• GetLockFilePath(path, dir) - Returns corresponding lock file path (campaign-aware)
• ListWorkflowFiles(dir, campaigns, generated) - Discovers workflows with filtering, returns structured WorkflowFile metadata
• WorkflowType enum and WorkflowFile struct for type-safe workflow representation

Usage

import "github.com/githubnext/gh-aw/pkg/cli/inventory"

// Extract from any path format
name := inventory.ExtractWorkflowName(".github/workflows/deploy.campaign.g.md")  // "deploy"

// Discover with filtering
workflows, _ := inventory.ListWorkflowFiles("", true, false)  // campaigns yes, generated no
for _, wf := range workflows {
    fmt.Printf("%s: %s -> %s\n", wf.Name, wf.Path, wf.LockPath)
}

README.md filters are case-insensitive and automatic. Campaign orchestrator .g.md files correctly map to their .campaign.lock.yml counterparts.

Test coverage: 97.1% (56+ test cases across 13 test functions)

Original prompt

Inventory helpers that extract / normalize workflow names from file names and organize, unify. Add tests.

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[pelikhan]

@copilot Merge main and recompile

[pelikhan]

@copilot add tests

[pelikhan]

@copilot unbloat this will, keep it short