fix: preserve special characters when dropping files into terminal

[4RH1T3CT0R7]

Fixes #276999

Problem

Dragging a file with special characters (~, `, !, #, $, ^, &, *, |, ;, <, >) in its name from the Explorer into the Terminal silently strips those characters from the path. This corrupts file paths and can cause users to unknowingly reference the wrong file.

Example: /home/user/file~v1.sh becomes '/home/user/filev1.sh' (tilde lost).

Root cause

escapeNonWindowsPath() contains a bannedChars regex that removes special characters from the path before quoting. Since the function already wraps paths in single quotes - where all characters are literal in POSIX shells (bash, zsh, sh, fish) and PowerShell - the stripping is unnecessary and actively harmful.

Fix

• Remove the bannedChars regex - single-quote wrapping already neutralizes all special characters
• Fix Fish bothQuotes handler - escape $ inside double-quoted paths (for the rare case where a path contains both ' and ")
• Fix PowerShell bothQuotes handler - escape ` and $ inside double-quoted paths

Test plan

• Updated unit tests: replaced "should remove dangerous characters" with tests verifying all 12 special characters are preserved
• Added tests for injection patterns ($(echo evil), `whoami`) confirming they are safely quoted
• Added tests for Fish and PowerShell bothQuotes $-escaping
• Updated 8 integration test expectations across all shell/platform combinations

[4RH1T3CT0R7]

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[Copilot]

Pull request overview

This PR fixes a bug where dragging files with special characters (like ~, `, !, #, $, ^, &, *, |, ;, <, >) from the Explorer into the Terminal would silently strip those characters from the path, corrupting file paths.

Changes:

• Removed the bannedChars regex that was stripping special characters from paths before quoting
• Added $ escaping in Fish shell's double-quoted path handler
• Added backtick and $ escaping in PowerShell's double-quoted path handler
• Updated unit and integration tests to verify special characters are preserved

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/vs/platform/terminal/common/terminalEnvironment.ts	Removed bannedChars regex; added $ escaping for Fish and $/backtick escaping for PowerShell in double-quoted paths
src/vs/platform/terminal/test/common/terminalEnvironment.test.ts	Replaced "dangerous characters" test with comprehensive tests for special character preservation and injection pattern safety
src/vs/workbench/contrib/terminal/test/common/terminalEnvironment.test.ts	Updated integration tests to expect $(echo evil) to be preserved in all shell types