feat: add desktop plans and native remote MCP

[killswitch-GUI]

Summary

• complete the Desktop Plan workflow and embedded terminal experience, including durable plan lifecycle/cancellation projections, API and SDK surfaces, tests, design QA, and architecture diagrams
• add native stateful MCP Streamable HTTP support for Splunk with bounded JSON/SSE responses, session handling, fresh schema discovery, and allowedTools: ["*"]
• add OAuth 2.1 PKCE bootstrap and refresh support with environment-backed client secrets, keyring/encrypted-state persistence, and CLI/TUI/worker authentication operations
• harden the remote MCP network and policy boundary with exact-origin authorization, DNS pinning, bounded bodies/timeouts, credential redaction, and process-vs-network effect enforcement
• regenerate public SDK bindings/examples and update event-listener to the RustSec-patched 5.4.2 release in root and Desktop lockfiles

Impact

Colossus can connect directly to current Splunk MCP endpoints without mcp-remote. Operators can choose explicit tool allowlists or opt into dynamic wildcard discovery while retaining schema validation, policy authorization, approvals, quarantine, and audit. Desktop users also receive the completed Plan lifecycle and terminal workflow.

Validation

• cargo xtask check rust
• cargo xtask pr --base origin/main
• generated SDK compatibility plus TypeScript, Python, and Go checks
• Desktop typecheck, 137 unit tests, security contracts, formatting, production build, and bundle-size check
• root, fuzz, and Desktop dependency policy/RustSec audits

Credential- or environment-gated live tests (Splunk, OPA, Chroma, OCI, and WORM) remain opt-in and were not run without configured endpoints.

[chatgpt-codex-connector]

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