feat(app): ship CostasCode with Copilot SDK bridge

[SlowGreek]

What this PR does

Ships CostasCode, a fully rebranded OpenCode-compatible desktop/CLI harness powered by an authenticated local GitHub Copilot SDK bridge for inference and provider-hosted web search only.

• Keeps sessions, agents, tools, permissions, compaction, persistence, protocol, server, CLI, and desktop orchestration inside CostasCode.
• Uses descriptor/challenge-authenticated loopback bridge transport with complete canonical history, store:false, parallel_tool_calls:false, stale-continuation retry, and no provider fallback.
• Exposes only github-copilot-sdk and bridge-discovered models; removes direct Copilot OAuth/provider paths and auth prompts.
• Removes Sentry, OTLP exporters, AI telemetry, PostHog/stats/reporting, direct Exa/Parallel search, and hosted OpenCode telemetry surfaces from production.
• Rebrands all user-facing copy, docs, menus, installer metadata, favicons, desktop icons, social images, TUI wordmark, and app title to CostasCode with a new “C” mark while preserving internal compatibility identifiers.
• Bundles the TypeScript-exporting Core workspace into Electron’s main process so the installed app never executes raw .ts files from node_modules.
• Enables General Settings auto-accept as a server-wide master switch even with no session open, while preserving explicit directory/session overrides.

Verification

• Root workspace typecheck passes across 21 package tasks.
• Root lint passes with zero errors.
• Focused bridge/provider/tool/search/telemetry/UI suites pass.
• Auto-accept fallback/override and prompt-submission suites pass (24 focused tests); app and Electron production builds pass.
• Electron packaging regression test passes, the generated main bundle has no external @opencode-ai/core imports, and the installed app reaches local server readiness.
• Hardened bridge launches with 0700/0600 state and challenge verification; live GPT-5.6-Sol exact-response proof succeeds through the desktop backend.
• CostasCode is packaged and installed at /Applications/CostasCode.app; the detached bridge remains running.

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