Enable provider retry by default

[ymichael]

What was wrong

The builtin Provider retry plugin was explicitly registered with defaultEnabled: false, so fresh installations shipped automatic subscription-limit recovery disabled even though the plugin is bundled and auto-installed.

What changed

• Enable provider-retry when its builtin registration is first installed while preserving the stored choice for existing installations.
• Add focused coverage for the fresh-install default and for preserving an existing disabled choice.
• Require the plugin to reach running in the packaged-app smoke test.
• Update configuration docs, CLI guides, the bb-cli skill, and the QA runbook to describe the new default.
• No server/host-daemon wire behavior changed; HOST_DAEMON_PROTOCOL_VERSION is unchanged.

How you verified

• pnpm exec turbo run typecheck --filter=@bb/server
• pnpm exec turbo run test --filter=@bb/server -- test/services/plugins/builtin-plugins.test.ts -t 'Provider retry enabled|preserves an installed builtin' (2 passed)
• Prettier check across all changed files
• The full builtin-plugin test file also passed the 22 unaffected/new cases; two existing source-watcher cases hit the local sandbox's EMFILE: too many open files, watch limit.

Fixes: no linked issue.

AGENT GENERATED: by GPT-5

[bb-slop-cop]

🚨 SLOP COP 🚨 · review

I am SlopCop. I am now reviewing this pull request for security, code quality, architecture, performance, and practical test coverage.

[bb-slop-cop]

🚨 SLOP COP 🚨 · review

Plain English summary: This PR enables automatic provider retries for new installations. It keeps the saved choice for current installations.

I found one medium issue:

• The manual mobile plugin flow still expects Provider retry to stay disabled.
• A fresh server now starts the plugin and shows its settings form.
• The flow will time out while it waits for the disabled settings view.
• Update that flow to check the enabled form, or disable the plugin before the check.

I found no security defect. The retry keeps the original permission mode and rejects newer requests or manual stops.

I found no blocking performance issue. The plugin adds small per-turn work and keeps small retry records until deletion or process exit.

The registry remains the correct source for the default. The packaged smoke list repeats the expected state by design, so no refactor helps here.

All GitHub checks passed. The Provider retry test package also passed all 25 tests. The exact-commit browser build did not finish its type generation.

Please fix the stale mobile flow and run it against a fresh server database.