Phase 6b/7b: per-child decoded periods, separate brief blocks, idempotent calendar (AUD-119)

- Parse each child's own "Today" day widget for the timetable (FR-16); drop the
  school-wide week calendar's lesson grid and clean the leaked routine rows.
- Add the editable codes map (FR-17): subjects, rooms, teachers and period
  labels, seeded, an unknown code falls back to the raw code; `school codes` CLI.
- Brief: Finn's block first, then Harry's, four sections always present (FR-9);
  periods decoded into plain English; the undated tail is one counted line (FR-18).
- Calendar: write periods + work due + work overdue + major events, per child,
  on every pass. Identity is the stable per-item key, so a re-run never re-inserts
  (FR-8). morning-brief.sh now runs scan -> calendar push -> notify.
- Day-widget labels are 12-hour: 1-6 read as PM, fixing afternoon periods.

Proven live on .13: image 0.6.2-phase6b7b; both children's briefs decoded and
separate; 35 events in calendar.school; runs 2 and 3 of the scan added nothing.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

internal/parse/daywidget.go

@@ -0,0 +1,114 @@
+package parse
+
+import (
+	"fmt"
+	"strings"
+	"time"
+)
+
+// This file parses the per-child day widget that Compass renders on a child's
+// own pages ("/Records/User.aspx?userId=..." and the Learning Tasks page). The
+// widget is labelled "Today" and its events are that child's own periods:
+//
+//	8:55: 1 - 7SCF - H14LAB - KNI
+//
+// The week calendar is school-wide (it carries the eldest child's lesson grid),
+// so it must never be the source of a child's timetable (AGENTS.md §4 FR-16).
+// This is the per-child source.
+
+// dayWidgetBaseHour is unused: the widget's grid start moves with the day's
+// first event (a page whose first event is 7:45 starts at 07:00, one whose
+// first event is 8:55 starts at 06:00), so the printed clock is the reliable
+// source and the grid offset is not.
+
+// parseDayWidget returns the periods in one child's day widget. found reports
+// whether the page carried a day widget at all.
+func parseDayWidget(child string, page Page, loc *time.Location, ref time.Time) (items []Item, found bool, err error) {
+	root := parseHTML(page.HTML)
+	events := findAll(root, func(n *node) bool {
+		return n.Tag == "div" && n.hasClassPart("day-bd-evt-") && n.hasClassPart("calendardaywidget-")
+	})
+	if len(events) == 0 {
+		return nil, false, nil
+	}
+
+	day := ref.In(loc)
+	if day.IsZero() {
+		day = time.Now().In(loc)
+	}
+	date := time.Date(day.Year(), day.Month(), day.Day(), 0, 0, 0, 0, loc)
+
+	for _, ev := range events {
+		labelSpan := find(ev, func(n *node) bool { return n.hasClass("ext-evt-bd") })
+		if labelSpan == nil {
+			continue
+		}
+		label := collapse(labelSpan.Text())
+		if label == "" {
+			continue
+		}
+		cm := clockPrefix.FindStringSubmatch(label)
+		if cm == nil {
+			return nil, true, fmt.Errorf("parse: %s: day-widget event %q has no start time", page.Slug, label)
+		}
+		at, err := dayWidgetTime(cm, date)
+		if err != nil {
+			return nil, true, fmt.Errorf("parse: %s: day-widget event %q: %w", page.Slug, label, err)
+		}
+		title := strings.TrimSpace(cm[3])
+		if title == "" {
+			title = label
+		}
+
+		subject, teacher, body := splitEvent(label, title)
+		url := page.URL
+		if url == "" {
+			url = compassHost + "/Organise/Calendar/"
+		}
+
+		items = append(items, Item{
+			Child:       child,
+			Source:      SourceCompass,
+			Type:        TypeEvent,
+			Subject:     subject,
+			Teacher:     teacher,
+			Title:       title,
+			Body:        body,
+			DueAt:       &at,
+			URL:         url,
+			SourcePage:  page.Slug,
+			ExternalRef: dedupeKey("day-period", at.Format(time.RFC3339), title),
+			Importance:  importanceNormal,
+		})
+	}
+	return items, true, nil
+}
+
+// dayWidgetTime reads an event's start from the printed clock. Compass prints a
+// 12-hour clock with no AM/PM marker ("1:26" is the afternoon period), so the
+// school-day convention applies: 1-6 are PM, 7-11 are AM, 12 is noon.
+func dayWidgetTime(clock []string, date time.Time) (time.Time, error) {
+	hour, minute := atoiSafe(clock[1]), atoiSafe(clock[2])
+	if hour < 0 || hour > 23 || minute < 0 || minute > 59 {
+		return time.Time{}, fmt.Errorf("bad time %02d:%02d", hour, minute)
+	}
+	if hour >= 1 && hour <= 6 { // 1:26 means 1:26 PM in the Compass day grid
+		hour += 12
+	}
+	return date.Add(time.Duration(hour)*time.Hour + time.Duration(minute)*time.Minute), nil
+}
+
+// atoiSafe parses a small decimal number, returning -1 when it is not one.
+func atoiSafe(s string) int {
+	n := 0
+	if s == "" {
+		return -1
+	}
+	for _, r := range s {
+		if r < '0' || r > '9' {
+			return -1
+		}
+		n = n*10 + int(r-'0')
+	}
+	return n
+}