Consolidate Unix CLI installation managers into a shared base

[bcotrim]

Related issues

• N/A

How AI was used in this PR

Claude Code traced the three platform installation managers and the shared dispatch in ipc-handlers.ts, then hoisted the duplicated Unix logic into a base class. All changes were reviewed manually; type-checking and the existing CLI unit test were run locally.

Proposed Changes

The macOS and Linux CLI installation managers were ~85% identical — shell-profile editing, symlink management, the standalone-install detection helpers, and the install/uninstall error-dialog handling were duplicated nearly verbatim, and all three platforms repeated the same auto-install try/catch shape.

This consolidates that shared logic into a single Unix base class that macOS and Linux extend, overriding only what is genuinely platform-specific (shell-profile filenames, default profile, the production CLI path, and macOS's legacy /usr/local/bin symlink cleanup). Windows keeps its registry/path mechanics but now reuses the shared error/info dialog and auto-install helpers.

Pure internal refactor: no behavior change — same dialogs, same shell-profile edits, same symlink handling, same Sentry/error reporting. Net ~240 fewer lines, making future changes to install behavior a single edit instead of three. No user-visible impact.

Testing Instructions

This is a behavior-preserving refactor, so existing CLI install/uninstall flows should work exactly as before:

• macOS/Linux: install the CLI from the app, confirm studio resolves and ~/.local/bin is added to the shell profile; uninstall and confirm the symlink is removed (and, on macOS, the legacy /usr/local/bin/studio is cleaned up).
• Windows: install/uninstall and confirm the PATH entry + proxy bat file behave as before.
• Standalone (curl) installs must still be detected and left untouched on all platforms.
• npm run typecheck (the only failures are pre-existing missing-bundled-dep errors unrelated to this change) and npm test -- apps/studio/src/modules/cli/lib/tests/cli-site-creator.test.ts pass.

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[wpmobilebot]

📊 Performance Test Results

Comparing 5de064d vs trunk

app-size

Metric	trunk	5de064d	Diff	Change
App Size (Mac)	1315.48 MB	1315.48 MB	0.01 MB	⚪ 0.0%

site-editor

Metric	trunk	5de064d	Diff	Change
load	1055 ms	1079 ms	+24 ms	⚪ 0.0%

site-startup

Metric	trunk	5de064d	Diff	Change
siteCreation	6487 ms	6513 ms	+26 ms	⚪ 0.0%
siteStartup	6987 ms	6964 ms	23 ms	⚪ 0.0%

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Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change (<50ms diff)