Add leading space to shell activation commands to prevent history bloating

[Copilot]

Activation commands (source /path/to/activate) were being saved to bash history on each terminal open, bloating history and making reverse-i-search unusable.

Changes

• Added shellsWithLeadingSpaceHistorySupport - Shells supporting HISTCONTROL=ignorespace (bash) or setopt HIST_IGNORE_SPACE (zsh): bash, zsh, gitbash
• Modified getShellCommandAsString - Prepends space for supported shells

// Before: "source /path/to/venv/bin/activate"
// After:  " source /path/to/venv/bin/activate"

Shell investigation

Shell	Leading space support
bash, zsh, gitbash	✅ Implemented
pwsh	Requires custom AddToHistoryHandler - not default
fish, sh, ksh, csh, nu	Not supported

Original prompt

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This section details on the original issue you should resolve

<issue_title>Bash activation command without proceeding space bloating bash-history</issue_title>
<issue_description>The activation of the venv is performed by command source $venv_path without space at the start. This result in this command stored multiple time in bash-history, bloating and overwriting it. This quickly makes reverse-i-search unusable.

Please use source $venv_path instead.</issue_description>

<agent_instructions>Investigate if we can do the same for other shells as well. Shell specific </agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Bash activation command without proceeding space bloating bash-history #604

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