Refresh CLI build toolchains and fix CI regressions

[igorcosta]

Build and release jobs currently pin Bun 1.2.22 independently, and one publication job uses an unpinned version. Declare Bun 1.4.2 once in package.json and have every CI/release job read it. Set Node.js 24 explicitly using setup-node v7, retain frozen installs, and add a regression check that prevents independent Bun pins from returning.

Full validation exposed test cleanup and stale terminal expectations. Restore mocked fetch after sync tests so subsequent WASM imports work, and align terminal assertions with the existing capitalized Autohand/Pro status line and teammate provider/model output.

The Windows installer also failed to split PATH entries, appending a duplicate install directory even when it was present. Split only on semicolons outside quotes and cover quoted paths containing semicolons; preserve the original PATH verbatim whenever an append is needed.

Write PATH backups with explicit UTF-8 without a byte-order mark so their text round-trips exactly across PowerShell versions. Simulate registry read failure explicitly in the fail-closed test instead of relying on platform behavior. Run independent platform builds alongside unit and terminal suites so CI reports all failures in one pass.

Validation: CI=true bun run proof passes on the final commit with Node 24.20.0/Bun 1.4.2: 8,588 unit tests, build, and all 91 terminal tests. Lint reports four existing warnings and no errors. All edited workflows pass actionlint 1.7.12. Both hosted CI runs pass unit and terminal suites plus macOS/Linux/Windows compilation and executable smoke checks, including Windows installer architecture and registry tests.

Final pull-request CI