[FEATURE]: TUI session list limited to 100 sessions + only 30-day window — no way to see older sessions

Problem

When scrolling through sessions in the TUI (<leader>l), only ~100 recent sessions are visible. Sessions older than 30 days or beyond the 100-session default are completely inaccessible from the TUI.

Root Causes

Two independent limits compound:

1. 30-day time window — sync.tsx line 363 filters sessions to only the last 30 days:

const start = Date.now() - 30 * 24 * 60 * 60 * 1000
const sessionListPromise = sdk.client.session
  .list({ start: start })

Any session older than 30 days simply never appears in the TUI list, even if under 100 sessions total.

2. 100-session default limit — session.ts line 731:

const limit = input?.limit ?? 100

The sync passes no limit parameter, so the server caps at 100. No pagination or "load more" exists in the TUI DialogSelect component.

Real-world impact: A user with 262 sessions spanning 5+ months can only scroll through the most recent ~100 from the last 30 days. The rest exist in the database but are invisible from the TUI.

Proposed Solution

At minimum:

• Increase or remove the 30-day start filter in the sync — or make it configurable
• Add pagination to the TUI session list (cursor-based, "load more" at scroll bottom, or virtual scrolling)

Stretch goals:

• Config option for session_list_limit in opencode.json
• Option to show all sessions (no time filter)

Related Issues

• #31513 — same hardcoded limit pattern but for messages within a session, not the session list itself
• #30109 — pagination broken when filtering by directory (related pagination issues)

Environment

• OpenCode: v1.14.19 (self-hosted binary)
• OS: Arch Linux
• Sessions in DB: 262 (700 MB)`