[codex] harden DeepSeek API format, context, and token budget

[j169476]

Summary

• Adapt OpenAI-compatible DeepSeek V4 API formatting: preserve reasoning_content, keep explicit empty reasoning_content values, serialize assistant tool-call content as an empty string where DeepSeek requires it, and omit tool_choice for DeepSeek V4 tool calls.
• Preserve DeepSeek reasoning_content from streaming and non-streaming responses so thinking blocks remain available before tool calls/text.
• Honor configured noninteractive models such as openai/deepseek-v4-pro when no explicit --model flag is supplied.
• Run runtime session compaction before outbound model requests, so oversized context is reduced before the provider call rather than only after a completed turn.
• Add a configurable single-turn token budget confirmation gate, defaulting to 100,000 tokens via CLAW_TURN_TOKEN_CONFIRM_THRESHOLD.
• Surface a dedicated CLI confirmation prompt when a turn exceeds the token budget.
• Remove tracked .claude / .claw session transcripts and expand .gitignore so local sessions, settings, plugin installs, and locally installed skills stay out of future commits.

Privacy / Local State

• Local API keys were not committed; staged additions were scanned for API key/token/secret patterns.
• The locally installed grill-me skill is treated as local operator state under .claw/skills/grill-me and is now ignored rather than committed. It influenced this work as a review posture, but it is not a project dependency.
• Note: because the upstream repository is public, an official GitHub fork inherits upstream history. This PR removes session artifacts from the branch tip and prevents future tracking, but it does not rewrite historical upstream commits.

Validation

• cargo check -p runtime --lib
• cargo check -p rusty-claude-cli
• git diff --check
• staged additions scanned for API key/token/secret patterns

Known Limits

• cargo fmt could not run because rustfmt is not installed for the local stable Windows toolchain.
• cargo test -p runtime --lib is currently blocked on Windows by existing Unix-only test code using std::os::unix::fs::PermissionsExt::set_mode in mcp_stdio.rs and mcp_tool_bridge.rs.