Remove primary wolt / WOLT_DIR legacy behavior

Problem

WOLT_DIR is a container-level env var set at boot by entrypoint_setup.py — it picks the first wolt found and makes it the "primary." This is a leftover from single-wolt days. In a multi-wolt system it's arbitrary and misleading.

Where WOLT_DIR is used (~12 files)

Container boot:

• entrypoint_setup.py — resolves first wolt → sets WOLT_DIR
• entrypoint.sh — tmux new-session -d -s main -c "$WOLT_DIR" (boot session), first-run viewport, TUI service

Server:

• server/config.py → app.py, tools.py — default memory dir, tool spawn dir

Bot:

• bot/core.py — active wolt context (has switch_wolt() to change at runtime)
• bot/telegram_adapter.py — default wolt dir

Other:

• tui-service.js — tmux session working dir
• cron/digest.mjs — memory/sparks dir

What's NOT affected

Sessions already work correctly — start_session() passes work_dir explicitly to tmux. WOLT_DIR is not used in session spawning code.

Proposed changes

1. Remove "pick first wolt" logic from entrypoint_setup.py — WOLT_DIR should not default to an arbitrary wolt
2. Replace main tmux session with a neutral landing (e.g. /workspace/wolts or no auto-boot) — sessions are spawned on demand via lodge/telegram/slack
3. Make server/bot wolt-agnostic — config.py, tools.py, core.py should derive context from the session, not a global env var
4. TUI service — should get working dir from the session being connected, not WOLT_DIR

Impact

Medium refactor. ~12 files to update. Low risk since sessions already bypass WOLT_DIR.

Found during investigation of nunu wolf cron failure — the "primary wolt" env leaked into a failed session's shell prompt, causing confusion.

🤖 Generated with Claude Code

Start by tracing WOLT_DIR through entrypoint_setup.py, entrypoint.sh, server/config.py, server/app.py, server/tools.py, bot/core.py, bot/telegram_adapter.py, tui-service.js, and cron/digest.mjs. Confirm the existing explicit work_dir handling in start_session(). Done means no arbitrary primary wolt is selected, the main session has a neutral landing or no auto-boot, and server, bot, TUI, and cron behavior no longer depends on the global WOLT_DIR.