feat: add dotflow viz — terminal pipeline visualization command

[avarga1]

Closes #108

What this adds

A new dotflow viz CLI command that renders any workflow as an ASCII pipeline diagram — no browser, no external service, zero new dependencies (uses rich which is already in the project).

$ dotflow viz -s my_pipeline.workflow

dotflow viz  ·  3 tasks  ·  mode: sequential

┌────────────────┐     ┌────────────────┐     ┌────────────────┐
│ extract        │ ──▶ │ transform      │ ──▶ │ load_data      │
│                │     │                │     │                │
│                │     │ retry: 3       │     │ timeout: 30s   │
└────────────────┘     └────────────────┘     └────────────────┘

Parallel mode stacks tasks with a fork bracket:

$ dotflow viz -s my_pipeline.workflow -m parallel

dotflow viz  ·  3 tasks  ·  mode: parallel

    ┌────────────────┐
    │ extract        │
  ┌─│                │
  │ └────────────────┘
  │
  ├─┌────────────────┐
  │ │ transform      │
  │ │ retry: 3       │
  │ └────────────────┘
  │
  └─┌────────────────┐
    │ load_data      │
    │ timeout: 30s   │
    └────────────────┘

Mermaid export for docs:

$ dotflow viz -s my_pipeline.workflow --format mermaid

graph LR
  extract --> transform
  transform --> load_data

Files changed

File	What
dotflow/utils/visualizer.py	Core rendering logic — box builder, sequential/parallel/group/mermaid renderers
dotflow/cli/commands/viz.py	VizCommand — wires the CLI args to the visualizer
dotflow/cli/commands/__init__.py	Exports VizCommand
dotflow/cli/setup.py	Registers dotflow viz subcommand with --step, --mode, --format args
tests/utils/test_visualizer.py	16 tests covering name resolution, box rendering, sequential, parallel, and mermaid output

Usage

# Sequential (default)
dotflow viz -s my_module.workflow

# Parallel
dotflow viz -s my_module.workflow -m parallel

# Mermaid export
dotflow viz -s my_module.workflow --format mermaid

[avarga1]

Hey @dotflow-io — just checking in on this one. Happy to address any feedback or rebase if needed. Let me know!

[FernandoCelmer]

🔍 Code Review

Code issues found: 2 blocking/suggestion + 5 inline guidance comments

#	Severity	Comment
1	[Blocking]	Background mode displays wrong label
2	[Suggestion]	Duplicate names break Mermaid output
3	[Suggestion]	Remove unnecessary inline comments in viz.py
4	[Suggestion]	Remove narration comments in visualizer.py
5	[Suggestion]	Use rich console instead of bare print()
6	[Suggestion]	Leverage rich Panel/Tree/Columns for rendering
7	[Comment]	Test structure feedback and missing test case

[FernandoCelmer]

Hey! 👋

Just a heads-up — this branch currently has merge conflicts with develop. Could you rebase or merge develop into your branch when you get a chance? That way we can get this reviewed and merged smoothly.

git checkout feature/ISSUE-108
git fetch origin
git merge origin/develop
# resolve conflicts
git push

---

💡 Tip: If you're using Claude Code, there's a git-flow skill that automates branch naming, commits, and rebasing following the project conventions:

👉 https://github.com/FernandoCelmer/skills/blob/master/skills/git-flow/SKILL.md

You can install it with:

claude plugins install git-flow@FernandoCelmer-skills

It handles the feature/ISSUE-NUMBER branch pattern and conventional commit messages automatically — super handy for keeping everything consistent!

[FernandoCelmer]

Hey! One more thing — could you rename the command from dotflow viz to dotflow flow? This applies to:

• The CLI subcommand registration (add_parser("viz", ...) → add_parser("flow", ...))
• The class name (VizCommand → FlowCommand)
• The file name (commands/viz.py → commands/flow.py)
• The setup method (setup_viz() → setup_flow())
• The __all__ export and imports
• Help texts and docstrings referencing "viz"

dotflow flow reads more naturally as a pipeline visualization command and aligns better with the project's naming conventions.