feat: add controlled plugin platform

[mahoshojoHCG]

Summary

• Adds a server-enforced preview → exact capability approval → install/upgrade flow with strict manifests, package-wide integrity signatures, dependency checks, publisher continuity, and crash-safe lifecycle recovery.
• Runs JavaScript out of process behind network/file/data capability brokers, bounded concurrency and resource budgets, circuit breaking, provider adapters, management APIs, Settings UI, SDK examples, and deployment persistence.
• Integrates notification and scoped-storage providers while keeping remote URL installation disabled.

Validation

• GitHub Actions: 47 plugin-process tests isolated from instrumentation; remaining 342 unit, 70 integration, and 4 FUSE tests passed with three Cobertura reports.
• Local: Release solution build (0 warnings/errors), full unit suite 389/389, frontend tests 16/16 and production build, changed-file format checks, and diff check.

Security boundaries

• Unsigned local packages require the explicit development-only opt-in. Worker limits use bounded concurrency plus process CPU/working-set monitoring rather than OS cgroups/job objects; production deployments should retain host/container resource and egress controls.
• Organization-specific NAT64/6rd/ISATAP translation needs host egress ACLs. On Windows, directory listing, metadata, and plugin-data writes fail closed until equivalent handle-relative operations are available.

Closes #16

[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-08-29T17:28:40.409933Z	6366329	PR opened

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Reviewed commit: 6366329ed7

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