[Enhancement] Build workflow from dict, add lib versioning

[zephyrzilla]

Summary

Adds the ability to build workflows from plain Python dictionaries (in addition to YAML files), and provides a library versioning pipeline across local dev, CI, and PyPI publishing.

Explain the features implemented:

Workflow.from_config() — build workflows from dicts

• New class method Workflow.from_config(config) accepts a dict or a file path, returning a ready-to-run Workflow instance
• ConfigLoader improvements — load_and_create() now correctly initialises _is_existing_task, _node_counter, and returns a typed Workflow

Single source of truth versioning

• sygra/__init__.py is now the sole version authority (__version__ = "2.0.0.post1")
• Hatchling reads it dynamically via dynamic = ["version"] + [tool.hatch.version] in pyproject.toml
• Version bumped to 2.0.0.post1 to match the current PyPI release (the 2.0.0 namespace was burned)

make version / make bump-version

• make version — prints the current version (stdlib python3, no uv run overhead)
• make bump-version V=X.Y.Z — patches both sygra/__init__.py and [tool.poetry].version atomically, with PEP 440 validation

Publish workflow updates (publish.yml)

• Dual trigger — fires on push: tags: v* (CLI) and release: published (GitHub UI), with a concurrency group to prevent double-runs
• Robust version extraction — handles both event types, with/without v prefix, validated against PEP 440
• PyPI pre-flight check — queries PyPI before building to fail fast if the version is already burned
• Artifact validation — verifies .whl and .tar.gz filenames contain the correct version before uploading

CI version guards (ci.yml)

• Tag trigger added — CI now runs on push: tags: v* in addition to branch pushes
• PEP 440 format check — always validates __version__ format (supports X.Y.Z, X.Y.Z.postN, etc.)
• Tag & code match — on tagged builds, validates the Git tag matches __version__ before proceeding

Pre-commit version hook

• New version-check hook validates __version__ is valid PEP 440 on every commit touching sygra/__init__.py

Performance impact (if any):

• N/A — no runtime performance changes. Build/CI pipelines gain early-exit validation.

How to Test the feature

Test Workflow.from_config():

1. Run the example script:

   from sygra.workflow import Workflow
   config = {
       "data_config": {"source": {"type": "disk", "file_path": "data.json", "file_format": "json"}},
       "graph_config": {
           "nodes": {"llm_1": {"node_type": "llm", "model": {"name": "gpt-4o"}, "prompt": [{"user": "Hello {text}"}]}},
           "edges": [{"from": "START", "to": "llm_1"}, {"from": "llm_1", "to": "END"}]
       }
   }
   wf = Workflow.from_config(config)

2. Verify wf.name, wf._is_existing_task, and wf._node_counter are set correctly

Test versioning:

1. make version: should print 2.0.0.post1
2. make bump-version V=2.1.0: patches both files, prints next steps
3. make bump-version V=bad: rejects with PEP 440 error
4. Revert: make bump-version V=2.0.0.post1

Test CI/publish (dry run):

1. Push a tag: the CI Validate version format step should pass
2. The publish workflow should extract the version, check PyPI availability, patch, build, validate artifacts

Screenshots (if applicable)

N/A — backend and CI/CD changes only.

Checklist

• Lint fixes and unit testing done
• End to end task testing
• Documentation updated