feat: Dynamic plugin load/unload and hide/unhide

[sandesh-sp]

Summary

Builds on the floating-panels foundation to add a full dynamic plugin lifecycle API.

• Dynamic plugin load/unload: Extends ToolControllerModern_ with deferred loading (startUnloaded config), a reverse toolId → targetId lookup map, hidden-state tracking, and explicit loadPlugin / unloadPlugin methods so plugins can be mounted and dismounted at runtime without a full page reload
• Public mmgisAPI surface: Exposes showPlugin, hidePlugin, loadPlugin, unloadPlugin, isPluginLoaded, isPluginHidden, showPanel, and hidePanel on mmgisAPI so external callers and other plugins can control visibility and lifecycle programmatically
• actionButtonLink events: Enhances action button link handling to fire both core events and plugin-scoped events, enabling cross-plugin communication via button actions

Test plan

• Set startUnloaded: true on a plugin; confirm it is registered as deferred and isPluginLoaded returns false
• Call mmgisAPI.loadPlugin(id) and confirm the plugin mounts and isPluginLoaded returns true
• Call mmgisAPI.unloadPlugin(id) and confirm destroy() is called and isPluginLoaded returns false
• Call mmgisAPI.hidePlugin(id) / showPlugin(id) and confirm the DOM element gains/loses the plugin-hidden class and isPluginHidden reflects the state
• Call mmgisAPI.hidePanel(id) / showPanel(id) on a float panel and confirm collapse/expand toggles correctly
• Verify destroyAllTools clears the deferred registry along with all loaded tools
• Confirm existing non-float panel layouts are unaffected
• Run npm test and confirm no regressions

Note: The Title Tool's actionButtonLink config is an easy way to test these features. Swapping its event type lets you trigger core events for showing/hiding and loading/unloading plugins

[github-actions]

✅ Version Already Updated

This PR includes a manual version update to 4.2.12-20260702

No automatic version bump needed.

[github-actions]

🤖 Version Auto-Bumped

The version has been automatically incremented to 4.2.12-20260702

This commit was added to your PR branch. When you merge this PR, the new version will be included.

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_{If you want a different version, update package.json manually and push to this PR.}

[CarsonDavis]

can we change to unloaded?