Add release infrastructure for PyPI publishing

[neuromechanist]

Summary

• Add version.py with centralized version management (0.2.0)
• Add bump_version.py script for semantic versioning with PEP 440 support
• Add PyPI publish workflow (TestPyPI on tags, PyPI on releases)
• Update pyproject.toml with enhanced metadata (keywords, classifiers, optional deps)
• Update README with PyPI badge and pip install instructions
• Apply ruff formatting and fix lint issues across codebase
• Update .gitignore with testing and dev entries

Test plan

• Tests pass (89 passed, 3 skipped)
• Package installs correctly
• Version imports correctly: import emgio; print(emgio.__version__)
• bump_version.py --current shows correct version
• Manual verification of PyPI workflow after merge

[codecov]

Codecov Report

❌ Patch coverage is 92.30056% with 83 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.65%. Comparing base (c878bbc) to head (e92e6c6).
⚠️ Report is 121 commits behind head on main.

Files with missing lines	Patch %	Lines
emgio/importers/eeglab.py	76.84%	22 Missing ⚠️
emgio/exporters/edf.py	75.36%	17 Missing ⚠️
emgio/core/emg.py	68.29%	13 Missing ⚠️
emgio/importers/wfdb.py	61.90%	8 Missing ⚠️
emgio/importers/csv.py	90.74%	5 Missing ⚠️
emgio/importers/edf.py	72.22%	5 Missing ⚠️
emgio/importers/otb.py	92.98%	4 Missing ⚠️
emgio/analysis/signal.py	81.25%	3 Missing ⚠️
emgio/importers/trigno.py	85.00%	3 Missing ⚠️
emgio/tests/test_core.py	99.43%	1 Missing ⚠️
... and 2 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #34      +/-   ##
==========================================
- Coverage   92.32%   90.65%   -1.68%     
==========================================
  Files          10       22      +12     
  Lines        1147     3038    +1891     
==========================================
+ Hits         1059     2754    +1695     
- Misses         88      284     +196     

Files with missing lines	Coverage Δ
emgio/__init__.py	100.00% <100.00%> (ø)
emgio/analysis/__init__.py	100.00% <ø> (ø)
emgio/analysis/verification.py	96.47% <100.00%> (ø)
emgio/importers/base.py	83.33% <ø> (ø)
emgio/tests/test_exporters.py	98.73% <100.00%> (-1.27%)	⬇️
emgio/tests/test_importer_wfdb.py	97.50% <100.00%> (ø)
emgio/tests/test_importers.py	96.46% <100.00%> (-0.17%)	⬇️
emgio/tests/test_verification.py	100.00% <100.00%> (ø)
emgio/tests/test_visualization.py	99.40% <100.00%> (ø)
emgio/visualization/__init__.py	100.00% <100.00%> (ø)
... and 12 more

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.