* agents: compile screen-detection rules from manifests

[[screen]] tables (state, title/bottom region, regex list, priority) are
compiled when a manifest loads; classify() picks the highest-priority match.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* server: classify hook-less panes from screen rules

A 500 ms tick matches the visible screen and title of live panes whose
current process has sent no hook; one Store transition maps the state to
lifecycle and attention.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* docs: record screen-detection rules (spec 027, ADR-0024)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

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Co-authored-by: Lucenx9 <185146821+Lucenx9@users.noreply.github.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>