Fix literal tildes in terminal-inserted paths - #9734

Summary

• Escape literal ~ characters in the shared terminal shell escaper used by paste, drag and drop, file explorer insertion, image transfer, and upload fallback paths.
• Add a behavior-level regression that creates ~md/Mobile Documents/invest, passes the cmux-escaped relative path to a clean /bin/zsh -f, and verifies that zsh enters the literal directory.
• Preserve the required red/green history: commit 1 adds the failing test; commit 2 fixes the shared escaper.

Refs #9680.

Issue analysis

The exact command in #9680 contains an unescaped space:

cd /Users/ren/Library/Mobile Documents/iCloud~md~obsidian/Documents/invest

That command is split into two arguments by zsh, which selects the documented cd old new form. Bare zsh and zsh with cmux integration sourced both emit the same string not in pwd error. Quoting the path or escaping the space succeeds. The mid-token iCloud~md~obsidian segment is not treated as named-directory syntax.

The investigation did uncover a related cmux-owned edge case: the shared app insertion escaper did not escape a literal tilde at the start of a token, so a relative path such as ~md/Mobile Documents/invest was interpreted by zsh as a named directory. This PR fixes that shared boundary and does not claim the cwd integration emitted the original error.

Testing

• Confirmed the new test fails before the fix with zsh:1: no such user or named directory: md.
• swift test --package-path Packages/macOS/CmuxTerminal --filter TerminalShellEscapingTests
• swift test --package-path Packages/macOS/CmuxTerminal (178 Swift Testing tests and 11 XCTest tests passed)
• ./scripts/reload.sh --tag issue-9680-cd-space-tilde-path
• Manually compared the reported unquoted command under bare zsh and cmux-integrated zsh; both returned status 1 with identical output. The quoted path returned status 0 and preserved spaces and mid-path tildes.

Demo Video

Not applicable: this is deterministic non-visual shell escaping behavior.

Checklist

• Tested locally
• Added behavior-level regression coverage
• No documentation or changelog update is needed
• Localization audit complete; no user-facing strings changed

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Summary by cubic

Escape literal ~ in terminal-inserted paths so zsh doesn’t treat them as home or named directories. Adds a regression test to cover ~md/... paths; addresses an edge case found while investigating #9680.

• Bug Fixes
  • Escape ~ in the shared terminal shell escaper used by paste, drag-and-drop, file explorer insertion, image transfer, and upload fallback.
  • Add a behavior test that creates ~md/Mobile Documents/invest, runs /bin/zsh -f, and verifies cd enters the literal directory.

^{Written for commit 4bfa6df. Summary will update on new commits.}