[P0][AGENT-04] Claude Code integration

Programme: #1
Epic: #20

## Objective
Integrate Claude Code through its supported structured CLI/SDK path while containing project hooks/configuration and normalizing its lifecycle into `AgentSession`.

## Scope
- Pin supported Claude Code versions and structured non-interactive invocation.
- Evaluate/use Agent SDK sidecar only where it materially improves lifecycle/tool control.
- Start from a clean confined environment before project hooks, commands or MCP config can run.
- Normalize progress, outputs, permission requests, artifacts, termination and diagnostics.
- Translate provider permissions to runtime proposals without granting ambient host access.
- Stage approved repository/worktree only.
- Version-specific compatibility tests for config/permission behavior.

## Security rules
- Project hooks, settings, skills and MCP configuration are untrusted repository inputs.
- Provider-internal shell/file/network capabilities must remain inside OS confinement unless fully mediated.
- No host home directory, vault, browser profile or unrelated context mounts.

## Acceptance criteria
- [ ] Malicious project hooks/config fixtures cannot escape the staged workspace/sandbox.
- [ ] Shared coding fixture produces normalized progress/artifacts and independently tested output.
- [ ] Cancellation reliably terminates provider execution and invalidates later authority.
- [ ] Provider permission prompts map to trusted runtime state or fail closed.
- [ ] Version drift/config changes are caught by golden/startup fixtures.
- [ ] No terminal-paint scraping is required for the supported path.

## Dependencies
- AGENT-02

**First phase:** P0
**Maturity target:** P3
**Owner:** harness-pc-providers

## Task issues
- [ ] #462 `AGENT-04.T01` — Pin CLI/SDK versions and choose integration mode
- [ ] #463 `AGENT-04.T02` — Confine before project discovery
- [ ] #464 `AGENT-04.T03` — Implement structured event decoding
- [ ] #465 `AGENT-04.T04` — Bridge permissions and scoped tool exposure
- [ ] #466 `AGENT-04.T05` — Implement interruption, resume and artifact review
- [ ] #467 `AGENT-04.T06` — Qualify hooks, MCP and coding outcomes

Begin with the AGENT-02 dependency and task issue #462, which covers CLI/SDK version pinning and integration mode. Then follow #463 through #467 for confinement, event decoding, permissions, interruption, artifacts, hooks, MCP and outcome qualification. Done means all listed acceptance criteria pass, including the security fixtures, normalized outputs, cancellation behavior and version-drift checks.

Written by the indexing model from the issue text.