Fix Claude-reported Base issues

[codeforester]

Summary

• Remove the hardcoded Rehearse the Homebrew upgrade contract for 1.0.0 #526 reference from the 1.0 Homebrew release reminder.
• Keep basectl ci setup --format json stdout parseable while preserving setup logs on stderr.
• Validate workspace manifest repos[].url values, document BASE_CI, and remove strict mode from the project installer template.

Validation

• BASE_HOME="$PWD" PYTHONPATH="$PWD/lib/python:$PWD/cli/python" /Users/rameshhp/.base.d/base/.venv/bin/python -m pytest cli/python/base_release/tests/test_engine.py cli/python/base_projects/tests/test_workspace_manifest.py -q
• BASE_HOME="$PWD" bats cli/bash/commands/basectl/tests/ci.bats cli/bash/commands/basectl/tests/repo.bats
• shellcheck -S error templates/project-install.sh cli/bash/commands/basectl/subcommands/ci.sh
• PYTHONPATH=lib/python:cli/python /Users/rameshhp/.base.d/base/.venv/bin/python -m pylint --rcfile=.pylintrc cli/python/base_projects/workspace_manifest.py cli/python/base_projects/tests/test_workspace_manifest.py cli/python/base_release/engine.py cli/python/base_release/tests/test_engine.py
• git diff --check
• git diff --cached --check
• env -u BASE_HOME ./bin/base-test

Closes #553
Closes #554
Closes #555
Closes #556
Closes #557