feat: Phase 4 grouping with entry-break dividers

Add group.py route, phase4.html template, and supporting state changes.
Photos are shown as a flat stream; clicking divider zones inserts
entry-break boundaries that split photos into labelled groups. Labels
persist via group_labels dict. Done materialises groups into state.groups
and advances to write phase.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

services/travel-memories/app/routes/group.py

@@ -0,0 +1,116 @@
+import uuid
+from flask import Blueprint, current_app, jsonify, redirect, render_template, request
+from app.state import Group, load_state, save_state
+
+bp = Blueprint("group", __name__)
+
+
+def _build_groups(state):
+    """Compute display groups from kept photos + dividers."""
+    kept = sorted(
+        [p for p in state.photos if p.tag in ("journal", "story")],
+        key=lambda p: p.order,
+    )
+    divider_orders = sorted(d["after_order"] for d in state.dividers)
+    divider_ids = {d["after_order"]: d["id"] for d in state.dividers}
+
+    groups = []
+    current_group = []
+    for photo in kept:
+        current_group.append(photo)
+        if photo.order in divider_orders:
+            div_id = divider_ids[photo.order]
+            groups.append({
+                "photos": current_group,
+                "divider_id": div_id,
+                "label": state.group_labels.get(div_id, ""),
+            })
+            current_group = []
+    if current_group:
+        groups.append({"photos": current_group, "divider_id": None, "label": ""})
+    return groups, kept
+
+
+@bp.get("/group")
+def group():
+    album_id = request.args["album_id"]
+    state = load_state(album_id, current_app)
+    groups, kept = _build_groups(state)
+    return render_template(
+        "phase4.html",
+        state=state,
+        groups=groups,
+        kept=kept,
+        current_phase="group",
+        album_id=album_id,
+        phase_stale=state.phase_stale,
+        notes_content=state.notes,
+    )
+
+
+@bp.post("/group/divider")
+def add_divider():
+    body = request.get_json()
+    state = load_state(body["album_id"], current_app)
+    after_order = int(body["after_order"])
+    if not any(d["after_order"] == after_order for d in state.dividers):
+        state.dividers.append({"id": str(uuid.uuid4()), "after_order": after_order})
+    save_state(state, current_app)
+    return jsonify({"ok": True})
+
+
+@bp.post("/group/remove-divider")
+def remove_divider():
+    body = request.get_json()
+    state = load_state(body["album_id"], current_app)
+    state.dividers = [d for d in state.dividers if d["id"] != body["divider_id"]]
+    state.group_labels.pop(body["divider_id"], None)
+    save_state(state, current_app)
+    return jsonify({"ok": True})
+
+
+@bp.post("/group/label")
+def set_label():
+    body = request.get_json()
+    state = load_state(body["album_id"], current_app)
+    state.group_labels[body["divider_id"]] = body["label"]
+    save_state(state, current_app)
+    return jsonify({"ok": True})
+
+
+@bp.post("/group/done")
+def done():
+    body = request.get_json()
+    state = load_state(body["album_id"], current_app)
+    groups, _ = _build_groups(state)
+    state.groups = []
+    for g in groups:
+        first_photo = g["photos"][0]
+        state.groups.append(Group(
+            id=str(uuid.uuid4()),
+            photo_ids=[p.id for p in g["photos"]],
+            entry_type=first_photo.tag,
+            date=first_photo.local_datetime[:10],
+            label=g["label"],
+        ))
+    if "group" not in state.phases_completed:
+        state.phases_completed.append("group")
+    state.phase = "write"
+    save_state(state, current_app)
+    return jsonify({"ok": True, "redirect": f"/write?album_id={body['album_id']}"})
+
+
+@bp.post("/group/from-note")
+def from_note():
+    body = request.get_json()
+    state = load_state(body["album_id"], current_app)
+    state.groups.append(Group(
+        id=str(uuid.uuid4()),
+        photo_ids=[],
+        entry_type="journal",
+        body=body.get("text", ""),
+    ))
+    if "write" in state.phases_completed and "write" not in state.phase_stale:
+        state.phase_stale.append("write")
+    save_state(state, current_app)
+    return jsonify({"ok": True})