Add the EDS calendar bridge

tests/quickshell/calendar-agenda-helper-contract.sh

@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+fail() {
+    printf 'calendar agenda helper contract: %s\n' "$1" >&2
+    exit 1
+}
+
+project_root="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
+helper="$project_root/config/dot/quickshell/scripts/calendar-agenda"
+
+[[ -x "$helper" ]] || fail 'helper is missing or not executable'
+
+probe="$($helper probe)"
+jq -e '.eds == true and .sourceRegistry == true and .enabledSources > 0' <<<"$probe" >/dev/null \
+    || fail 'EDS readiness probe failed'
+
+range_start="$(date +%s)"
+range_end="$((range_start + 1209600))"
+snapshot="$($helper query "$range_start" "$range_end")"
+
+jq -e '
+    .ok == true and
+    (.sources | type == "array" and length > 0) and
+    (.events | type == "array") and
+    ([.sources[] | (keys | sort) == (["id", "name", "color"] | sort)] | all) and
+    ([.events[] | (keys | sort) == (["id", "sourceId", "uid", "summary", "start", "end", "allDay", "location", "joinUrl"] | sort)] | all)
+' <<<"$snapshot" >/dev/null || fail 'live snapshot shape is invalid'
+
+printf 'calendar agenda helper contract: PASS (%s sources, %s events; contents redacted)\n' \
+    "$(jq '.sources | length' <<<"$snapshot")" \
+    "$(jq '.events | length' <<<"$snapshot")"