Add macOS Helium browser cookie import

[manjoot]

Human comments

What was wrong

Helium on macOS was missing from the browser registry and shared source-ID schema, so BB's existing cookie importer could not discover or import its profiles.

What changed

Register Helium with its profile directory, process/app name and Keychain identity. The existing settings picker, Chromium reader, SDK and CLI handle the import. Support is macOS-only and remains a one-time copy.

Add helium to the shared source schema and bump HOST_DAEMON_PROTOCOL_VERSION from 214 to 215: the old schema rejects the new ID in both requests and discovered-source results. Also bump the plugin SDK from 0.4.103 to 0.4.104 using the repository script. The generated SDK declarations include the source IDs, so adding Helium changes its published types. Update the browser guide and CLI skill.

How you verified

• After rebasing onto current main: 24 desktop/broker tests and 42 contract tests pass on Node 22.19.0, along with desktop, contract, and SDK typechecks. The protocol-version assertion now expects 215.

• Two regression tests cover importing a selected non-default profile with Helium's Keychain identity and recognising its profile lock. They use real SQLite fixtures with fake OS and Electron calls. Both fail without the Helium registry entry. Five deliberate faults in profile selection, path, Keychain service/account and process name fail the relevant assertions.

• On Node 22.19.0: 24 desktop/broker, 42 contract, 12 settings, 3 CLI and 1 SDK-version tests pass. Desktop/contract/SDK typechecks, desktop/SDK builds, formatting, lint, whitespace and the SDK npm version guard pass. Existing build warnings remain.

• The contributor tested Helium 0.17.0.1 on macOS, completed the real Keychain prompt and imported 1,446 cookies with 299 skipped. Graphite opened signed in. The contributor also reports testing restart persistence in add helium on macOS to the browser cookie importer #3841; the automated tests do not establish that.

pnpm exec turbo run test --filter=@bb/desktop --filter=@bb/host-daemon-contract -- browser-import desktop-browser-broker-import contract.test
pnpm exec turbo run test --filter=@bb/app --filter=@bb/cli -- BrowserSettingsSection browser-import-wizard command-output/browser
pnpm exec turbo run test --filter=@get-bb/plugin-sdk -- version.test
pnpm exec turbo run typecheck --filter=@bb/desktop --filter=@bb/host-daemon-contract --filter=@get-bb/plugin-sdk
pnpm exec turbo run build --filter=@bb/desktop --filter=@get-bb/plugin-sdk
node packages/plugin-sdk/scripts/check-npm-version-guard.mjs

Fixes #3841

AGENT GENERATED