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/tests/fixtures/phase2_state.json

@@ -14,5 +14,7 @@
      "local_datetime": "2023-09-06T10:00:00", "tag": "untagged", "order": 2}
   ],
   "groups": [],
-  "notes": ""
+  "notes": "",
+  "dividers": [],
+  "group_labels": {}
 }

services/travel-memories/tests/fixtures/phase3_state.json

@@ -14,5 +14,7 @@
      "local_datetime": "2023-09-06T10:00:00", "tag": "skip", "order": 2}
   ],
   "groups": [],
-  "notes": ""
+  "notes": "",
+  "dividers": [],
+  "group_labels": {}
 }

services/travel-memories/tests/fixtures/phase4_state.json

@@ -12,5 +12,7 @@
      "local_datetime": "2023-09-05T14:30:00", "tag": "story", "order": 1}
   ],
   "groups": [],
-  "notes": "I remember the airport was chaos."
+  "notes": "I remember the airport was chaos.",
+  "dividers": [],
+  "group_labels": {}
 }

services/travel-memories/tests/fixtures/phase5_state.json

@@ -14,16 +14,18 @@
   "groups": [
     {
       "id": "g1", "photo_ids": ["asset-1"], "entry_type": "journal",
-      "title": "", "body": "", "location_city": "", "location_country": "",
+      "label": "", "title": "", "body": "", "location_city": "", "location_country": "",
       "date": "2023-09-05", "hero_photo_id": null, "shortcode_hints": "",
       "status": "draft"
     },
     {
       "id": "g2", "photo_ids": ["asset-2"], "entry_type": "story",
-      "title": "", "body": "", "location_city": "", "location_country": "",
+      "label": "", "title": "", "body": "", "location_city": "", "location_country": "",
       "date": "2023-09-05", "hero_photo_id": null, "shortcode_hints": "",
       "status": "draft"
     }
   ],
-  "notes": "I remember the airport was chaos."
+  "notes": "I remember the airport was chaos.",
+  "dividers": [],
+  "group_labels": {}
 }

services/travel-memories/tests/fixtures/phase6_state.json

@@ -14,18 +14,20 @@
   "groups": [
     {
       "id": "g1", "photo_ids": ["asset-1"], "entry_type": "journal",
-      "title": "Arrival in Almaty", "body": "Chaos at the airport.",
+      "label": "", "title": "Arrival in Almaty", "body": "Chaos at the airport.",
       "location_city": "Almaty", "location_country": "Kazakhstan",
       "date": "2023-09-05", "hero_photo_id": "asset-1", "shortcode_hints": "",
       "status": "written"
     },
     {
       "id": "g2", "photo_ids": ["asset-2"], "entry_type": "story",
-      "title": "The Market", "body": "Colours everywhere.",
+      "label": "", "title": "The Market", "body": "Colours everywhere.",
       "location_city": "Almaty", "location_country": "Kazakhstan",
       "date": "2023-09-05", "hero_photo_id": "asset-2", "shortcode_hints": "gallery block",
       "status": "skipped"
     }
   ],
-  "notes": ""
+  "notes": "",
+  "dividers": [],
+  "group_labels": {}
 }

services/travel-memories/tests/test_phase4.py

@@ -0,0 +1,47 @@
+import json
+
+
+def test_photos_shown_as_stream(base_url, page, seed_state):
+    album_id = seed_state("phase4_state")
+    page.goto(f"{base_url}/group?album_id={album_id}")
+    assert page.locator(".stream-photo").count() == 2
+
+
+def test_insert_divider_creates_group_boundary(base_url, page, seed_state, flask_app):
+    album_id = seed_state("phase4_state")
+    page.goto(f"{base_url}/group?album_id={album_id}")
+    page.locator(".divider-zone").first.hover()
+    page.locator(".insert-divider-btn").first.click()
+    page.wait_for_timeout(300)
+    assert page.locator(".group-block").count() == 2
+
+
+def test_remove_divider_merges_groups(base_url, page, seed_state):
+    album_id = seed_state("phase4_state")
+    page.goto(f"{base_url}/group?album_id={album_id}")
+    page.locator(".divider-zone").first.hover()
+    page.locator(".insert-divider-btn").first.click()
+    page.wait_for_timeout(200)
+    page.locator(".remove-divider-btn").first.click()
+    page.wait_for_timeout(200)
+    assert page.locator(".group-block").count() == 1
+
+
+def test_label_edit_persists(base_url, page, seed_state, flask_app):
+    album_id = seed_state("phase4_state")
+    page.goto(f"{base_url}/group?album_id={album_id}")
+    page.locator(".divider-zone").first.hover()
+    page.locator(".insert-divider-btn").first.click()
+    page.wait_for_timeout(200)
+    page.locator(".group-label").first.fill("Morning walk")
+    page.locator(".group-label").first.press("Enter")
+    page.wait_for_timeout(300)
+    page.reload()
+    assert "Morning walk" in page.locator(".group-label").first.input_value()
+
+
+def test_done_advances_to_write(base_url, page, seed_state):
+    album_id = seed_state("phase4_state")
+    page.goto(f"{base_url}/group?album_id={album_id}")
+    page.locator("#done-btn").click()
+    page.wait_for_url("**/write**")