Add reload action for disk plugins

[bostonaholic]

Why

Plugins installed from a local folder currently require another import flow to pick up local edits. Settings should let users reload the saved folder install directly without wiping memory-only state from a running plugin.

What

• Store reload metadata for folder installs and expose a native plugin_reload command.
• Add a Reload action for reloadable external plugins while they are disabled.
• Reject reload for enabled plugins so memory-only plugin state, such as credentials, is not discarded by replacing the running module.
• Keep Git installs and older installs non-reloadable, and document the behavior.

Reload Scope

This first version reloads only disabled plugins. A true hot reload needs a plugin lifecycle that can hand state from the running module to the replacement module; Buzz does not have that contract yet. Requiring the user to disable the plugin first prevents reload from dropping memory-only state such as tokens, active subscriptions, or other runtime data.

Screenshots

buzz-reload-plugin-demo-default-rerecord.mp4

Test plan

• Verified plugin-manager reload behavior, rollback metadata, enabled-plugin rejection, invalid source rejection, and symlink replacement rejection.
• Verified plugin manager storage flow with unit tests.
• Verified Settings folder import/reload path in Chromium browser test.
• Ran typecheck and Biome check.

Notes

• Full browser config could not run locally because WebKit is not installed; the changed spec passed with Chromium and --no-deps.
• Screenshots were captured locally, but GitHub CLI refused attachment upload without upstream repository write access.

[bostonaholic]

@codex review