feat(tui): hydrate pending session work

[opencode-agent]

What

• Fetch session.pending.list when refreshing TUI session messages.
• Merge pending user/synthetic inputs and compaction barriers into local message state.
• Track pending user/synthetic IDs so existing row rendering keeps them queued until promotion.
• Render live session.compaction.admitted barriers immediately and reconcile them with session.compaction.started.

Tests

• bun typecheck from packages/tui
• bun test test/cli/tui/data.test.tsx from packages/tui

Note: initial bun install failed because node-gyp is not installed for native scripts; bun install --ignore-scripts completed and the TUI checks above pass.

[kitlangton]

Superseded by #36433, which will hydrate from the pending API with a deterministic promotion-race regression.