feat: add CodeBuddy CLI harness adapter

[aleexjiang]

Summary

Integrates the Tencent CodeBuddy CLI as a new external Harness, so its Agent runs as a native Thread inside Codex Desktop — alongside Pi, Claude Code, DeepSeek Harness, OpenCode, Grok, and OMP.

The adapter follows the repos native-interface integration approach (see .agents/skills/codexhost-add-harness): it drives the CodeBuddy CLI over its **bidirectional stream-json print transport** (-p --output-format stream-json --input-format stream-json --include-partial-messages`) and keeps one CLI process alive across Turns, projecting frames into the standard HarnessAdapter contract.

What is supported

• Sessions: create / resume via --resume <sessionId> (fork and rollback are reported as unsupported)
• Streaming: text and reasoning deltas projected from stream_event frames, with an assistant-text fallback for CLI builds that skip deltas
• Tools: tool_use / tool_result projected into commandExecution / toolExecution items (Bash/PowerShell mapped to command execution)
• Permission modes: selected at Session creation via --permission-mode; unattended-full-access delegation maps to bypassPermissions
• Model Catalog: parsed from codebuddy --help, filtered to transport-safe Model Ref IDs, with a static fallback catalog
• Usage: token counters, context window / context-used, and total cost from the terminal result frame
• History: transcript snapshots parsed from ~/.codebuddy/projects/<slug>/<sessionId>.jsonl (with project-slug scan fallback); Native Turn Refs keyed by persisted user-message ids
• Cancellation: kills the CLI process; the next Turn re-spawns with --resume

Explicitly not supported (reported, never silently degraded)

• Interactive approvals / questions (the print transport has no approval channel)
• Mid-session model / thinking / permission-mode switching (CLI fixes configuration at process start)
• Fork and rollback

Wiring

• packages/adapters/codebuddy — new adapter package (transport, accumulator, usage, history, discovery, model catalog, session/adapter)
• protocol-core — codebuddy added to EXTERNAL_HARNESS_IDS, transport Model codec (codexhost/codebuddy-native, encodes model + permission mode)
• host-runtime — adapter registration, CODEXHOST_CODEBUDDY_COMMAND override, approval-server naming, package metadata
• renderer-extension — agent selection state, binding probe, transport model codec, icon/labels, picker, sidebar, connections page
• Root tsconfig references, host-runtime dependencies, package-lock
• README (zh/en/ko): badge, intro, and feature-status matrix

Testing

• npx tsc -b — clean (also tsc -p tests/tsconfig.json --noEmit)
• vitest run — 185 files / 1595 tests passing, including 40 new tests covering frame parsing, turn projection, usage mapping, transcript history, and the full create → turn → stream → complete / cancel / crash lifecycle against a fake child process
• eslint / prettier --check — clean for all touched files

Note: two pre-existing eslint errors exist in packages/adapters/opencode/src/opencode-adapter.ts (non-null assertions at lines 1726/1736) on the untouched main code; left as-is to keep this PR focused.

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