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/calendar.go

@@ -6,6 +6,8 @@ import (
 	"strconv"
 	"strings"
 	"time"
+
+	"gitea.lab.audasmedia.com.au/sam/compass_teams_nhs/internal/period"
 )
 
 // calendarPxPerHour is the Compass week-grid scale: the day gutter is 1200px
@@ -21,13 +23,12 @@ var (
 	calendarTop = regexp.MustCompile(`top:\s*([0-9.]+)px`)
 	// clockPrefix matches the leading "8:55: " of an event label.
 	clockPrefix = regexp.MustCompile(`^(\d{1,2}):(\d{2}):\s*(.*)$`)
-	// periodLabel matches the period part of a lesson label: "5", "C" or
-	// "RLE GROUP D".
-	periodLabel = regexp.MustCompile(`^(\d{1,2}|[A-Z]|RLE GROUP [A-Z])$`)
 )
 
-// parseCalendar parses the week calendar into event items. It fails loudly when
-// the page has no calendar grid (FR-12).
+// parseCalendar parses the week calendar page. The week calendar is
+// school-wide and its lesson grid belongs to the eldest child, so routine
+// lessons are dropped here: each child's own periods come from that child's
+// day widget (FR-16). Only real school events are kept.
 func parseCalendar(child string, page Page, loc *time.Location) ([]Item, error) {
 	items, found, err := extractCalendar(child, page, loc)
 	if err != nil {
@@ -36,7 +37,13 @@ func parseCalendar(child string, page Page, loc *time.Location) ([]Item, error)
 	if !found {
 		return nil, fmt.Errorf("parse: %s: no calendar grid found in %s (layout changed or fetch failed)", child, page.Slug)
 	}
-	return items, nil
+	out := items[:0]
+	for _, it := range items {
+		if eventIsSchoolEvent(it.Title) {
+			out = append(out, it)
+		}
+	}
+	return out, nil
 }
 
 // extractCalendar returns the calendar events in one page. found reports whether
@@ -140,8 +147,8 @@ func eventItem(child string, ev *node, page Page, loc *time.Location) (Item, boo
 // label is "5 - 11HLEGB5 - D8 - LHT"; a school event is
 // "End of Year Senior Music Concert - HALL (...) - KSH, CFR, ...".
 func splitEvent(label, title string) (subject, teacher, body string) {
-	parts := splitDash(title)
-	if len(parts) >= 2 && periodLabel.MatchString(parts[0]) {
+	parts := period.SplitDash(title)
+	if len(parts) >= 2 && period.IsPeriodLabel(parts[0]) {
 		for _, p := range parts[1:] {
 			if subject == "" && classCode.MatchString(p) {
 				subject = p
@@ -159,11 +166,4 @@ func splitEvent(label, title string) (subject, teacher, body string) {
 }
 
 // splitDash splits on " - " and trims each part.
-func splitDash(s string) []string {
-	raw := strings.Split(s, " - ")
-	out := make([]string, 0, len(raw))
-	for _, p := range raw {
-		out = append(out, strings.TrimSpace(p))
-	}
-	return out
-}
+func splitDash(s string) []string { return period.SplitDash(s) }