menu bar app: live agent states from tmux pane options

single-file appkit status item (menubar/main.swift, LSUIElement) polling
@agent/@agent_state pane options every 2s: counts in the bar, per-pane
rows with click-to-focus via switch-client. daemon now also writes an
@agent label per pane so the menu bar and tmux status-right can render
agent names without duplicating identification logic.

wait for tmux at startup, force utf-8 for tmux clients, add launchd packaging

running under launchd, the tmux client defaults to the c locale, which
makes tmux mangle tab-separated -f output into underscores, so every
pane parsed as one field and the watcher silently saw nothing; invoke
tmux with -u so format output is locale-independent. drop the startup
fail-fast: the watcher now waits for a tmux server and attaches when one
appears, which is the right shape for a login agent. ship the launchd
plist under packaging/launchd.

initial dingger: tmux agent watcher with herdr's detection engine

extract detect-core from herdr's src/detect (engine + 22 manifests,
tests unchanged) and add the dingger binary: tmux capture-pane watcher,
process-tree agent identification, herdr's notification policy, embedded
notification sounds, @agent_state write-back, and catalog-based manifest
refresh. viewer screens are non-observations per the engine contract;
reviewed by a three-model panel (opus 5.5, gpt 6.1 sol, kimi k3) with
all confirmed findings applied as deletions.