[Atomic 16] Add TerminalFeed container with pause/resume and tail-lock

[clawgreen]

Goal

Create a high-level TerminalFeed container for streaming logs.

Why

Current pieces exist, but no single opinionated feed container ties them together.

Scope (atomic)

• New container component with:
  • pause/resume stream view
  • tail-lock toggle
  • jump-to-latest action
  • max buffer cap
• Compose existing primitives where possible.

Acceptance Criteria

• Works with dynamic incoming data.
• Tail behavior is predictable.
• No breaking changes to existing components.

[clawgreen]

Recommended Execution\n- Order: 16 / 17\n- Keep this PR atomic (single-purpose; avoid cross-issue scope).\n- Target PR size: ~50-200 LOC when possible.\n- Dependency: #15.\n- Suggested branch pattern: codex/atomic-16-....