Official catalog plugins pin ^0.5.0 and are uninstallable on SDK 0.4.3

[SawyerHood]

Problem

#1569 returns the plugin SDK to 0.4.3, because the 0.4.2 to 0.5.0 bump in #1360 was a marker rather than a break, and it unloaded every installed plugin carrying a caret range.

Two Git official catalog entries in apps/server/src/services/plugins/builtin-registry.ts still declare bbPluginSdkRange: "^0.5.0":

• thread-hover-cards (line ~191)
• improve-prompt / prompt-shaper (line ~205)

Their floor (0.5.0) is above the host SDK (0.4.3), so Extensions disables both install buttons and shows an SDK incompatibility. This was confirmed by running the dev server at that SHA.

Why it was not fixed in #1569

The registry entries are static mirrors of manifests pinned in github.com/brsbl/bb-plugins. Lowering only the registry entry would re-enable the install button and then fail later against the real manifest, which is worse than a disabled button with a clear reason. So the entries were deliberately left accurate.

Fix

1. Lower engines.bbPluginSdk to a floor range (>=0.4.3) in both plugin manifests in brsbl/bb-plugins.
2. Re-pin gitSource in builtin-registry.ts to the new commits.
3. Update bbPluginSdkRange in both catalog entries to match.
4. Add a catalog test asserting every official entry satisfies the current SDK, so a stale version list cannot ship again. This test cannot be added before step 1, because it would fail on the entries as they stand.

Impact

Until this is done, these two plugins cannot be installed from the Extensions store. Already-installed copies are unaffected, since their manifests are evaluated against the same floor rule.

AGENT GENERATED: by Claude Opus 5

[SawyerHood]

Upstream issue filed: brsbl/bb-plugins#29.

It documents why the fix cannot land there yet: that repository pins its toolchain to bb release 0.37.0, which shipped SDK 0.5.0. The vendored SDK archive, the vendored bb plugin build bundle (which stamps every dist/*.meta.json), and two exact-equality validators all assert ^0.5.0. SDK 0.4.3 exists only on bb main.

So this is blocked on a bb release containing SDK 0.4.3. Once that ships, the upstream change is: re-vendor the SDK and build tool, relax the two validators to floor semantics, set the five manifests to >=0.4.3, rebuild, and re-pin the commits in builtin-registry.ts.