fix(workspace): support jump and auto-follow in agent terminal views

[Juliusolsson05]

Problem

Jump to Latest and Auto-follow Focused Agent are gated behind the rendered feed. Raw agent terminal views, including OpenCode Terminal, do not consume the existing jump/follow state. Tail All likewise affects rendered feeds only.

Expected Behavior

The existing commands operate on raw agent terminal views without switching surfaces. Tail All follows every visible agent surface. Plain shell terminals remain unchanged. Disabling follow preserves the pre-follow reading position where that content remains available.

Evidence and Reproduction

Open an agent in its terminal surface, scroll back, then use Jump to Latest or enable auto-follow. The original commands are hidden by requires-rendered-feed and AgentTerminalLeaf has no scroll-intent consumer. Scope is Claude/Codex raw views and OpenCode Terminal, not a new provider.

Acceptance Criteria

• Jump and per-agent/Tail All follow work in raw agent views.
• Hidden panes, session changes, asynchronous writes, and scrollback trimming cannot corrupt restored positions.
• Renderer integration tests and real xterm regression coverage protect these boundaries.
• Claude and Codex review findings are resolved; verified changes land through a linked PR.

Implementation branch: feat/agent-terminal-follow. Initial plan committed before implementation; issue recorded during review to restore the requested tracking convention.

[Juliusolsson05]

Implemented in PR #838. Both the Claude and Codex MCP reviewers approved integrated revision 25eabfc after their initial findings were fixed. Final local Node 24 verification: typecheck passed, 563 renderer tests passed, 111 system tests passed including a new real Electron/xterm regression. One unrelated local provenance assertion is tracked separately in #839. Awaiting CI before the user-authorized merge; this issue will close through the resolving PR, not manually.