fix: add .venv/ to gitignore templates and remove duplicate .env entry

[notgitika]

Description

.venv/ (the default python -m venv .venv directory) was missing from all 6 Python framework gitignore templates, causing virtual environment files (hundreds of MB of third-party packages) to be staged on git add. Also removes a duplicate .env entry in the Strands template.

Related Issue

Closes #332

Documentation PR

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Other (please describe):

Testing

How have you tested the change?

All

• I ran npm run test:unit and npm run test:integ
• I ran npm run typecheck
• I ran npm run lint
• If I modified src/assets/, I ran npm run test:update-snapshots and committed the updated snapshots

Checklist

• I have read the CONTRIBUTING document
• I have added any necessary tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly
• I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• My changes generate no new warnings
• Any dependent changes have been merged and published

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[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	28.26%	1807 / 6393
🔵	Statements	27.59%	1875 / 6794
🔵	Functions	27.36%	356 / 1301
🔵	Branches	24.52%	918 / 3743

Generated in workflow #406 for commit 5e6a884 by the Vitest Coverage Report Action

[aidandaly24]

nice