Add task graph export with JSON, DOT, and text output

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What this task asks for

Add a graph export command for tasks with JSON, DOT, and text output, including reverse traversal and status control. Add a `--graph` view with JSON, DOT, and indented text formats. Include roots, node metadata, dependency and command edges, depth groups, and longest path in JSON output. Mark up-to-date DOT nodes as dashed and suppress status fields or styling under `no-status`. Support reverse dependency traversal across the complete Taskfile. Resolve aliases, wildcards, includes, defaults, and for-loop expansions consistently. Report missing tasks and dependency cycles with errors that name the affected tasks.