fix(happy-coder): return raw Codex approval decisions

[0809android]

Summary

• register the Codex approval handler on the raw elicitation/create method instead of setRequestHandler(ElicitRequestSchema, ...)
• return the top-level { decision } shape that codex mcp-server expects
• normalize approved_for_session to approved and reject unsupported / incomplete requests with abort
• add coverage for raw handler registration and Codex decision normalization

Why

I was reproducing the Android permission flow issue from #229 with Codex sessions.

In practice, codex mcp-server currently expects a non-standard top-level approval response like:

{ "decision": "approved" }

Using the MCP SDK's standard elicitation handler path returns the SDK-shaped payload instead, which causes Codex to reject the approval response and the command stays stuck or ends up rejected after approval.

This patch keeps the existing Happy permission flow, but installs the Codex approval handler on the raw request map so the response shape matches what Codex actually consumes today.

Testing

• PATH=/Users/kinocode/.nvm/versions/node/v22.19.0/bin:$PATH yarn install
• PATH=/Users/kinocode/.nvm/versions/node/v22.19.0/bin:$PATH yarn workspace happy-coder build
• PATH=/Users/kinocode/.nvm/versions/node/v22.19.0/bin:$PATH ./node_modules/.bin/vitest run packages/happy-cli/src/codex/__tests__/codexMcpClient.test.ts
• Manual validation against codex mcp-server 0.106.0
  • SDK-standard { action, content } approval responses failed with missing field decision
  • raw { decision: "approved" } resumed the command successfully
  • raw { decision: "abort" } produced the expected rejected by user