feat: Phase 1 album selection with resume/start-over

Implements GET / listing Immich albums with resume badge, POST /select
creating TripState and redirecting to /triage; graceful error display
when Immich is unreachable.

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

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

@@ -1,9 +1,76 @@
-from flask import Blueprint, current_app, render_template, request
-from app.state import load_state
+from pathlib import Path
+
+from flask import Blueprint, current_app, redirect, render_template, request
+from app.immich import ImmichClient
+from app.state import TripState, Photo, load_state, save_state
 
 bp = Blueprint("albums", __name__)
 
 
+def _client():
+    return ImmichClient(current_app.config["IMMICH_URL"],
+                        current_app.config["IMMICH_API_KEY"])
+
+
+@bp.get("/")
+def index():
+    try:
+        albums = _client().list_albums()
+        error = None
+    except ConnectionError as e:
+        albums = []
+        error = str(e)
+    state_dir = Path(current_app.config["STATE_DIR"])
+    for album in albums:
+        album["has_state"] = (state_dir / f"{album['id']}.json").exists()
+    return render_template("phase1.html", albums=albums, error=error,
+                           current_phase="", album_id=None,
+                           phase_stale=[], notes_content="")
+
+
+@bp.post("/select")
+def select():
+    album_ids = request.form.getlist("album_ids[]")
+    grav_trip_slug = request.form["grav_trip_slug"].strip()
+    start_over = request.form.get("start_over") == "1"
+
+    if len(album_ids) == 1:
+        primary_id = album_ids[0]
+    else:
+        primary_id = "__merged__" + "_".join(sorted(album_ids))
+
+    existing = load_state(primary_id, current_app)
+    if existing and not start_over:
+        return redirect(f"/{existing.phase}?album_id={primary_id}")
+
+    # Fetch and merge assets, deduplicating by asset ID
+    all_assets = {}
+    album_name_parts = []
+    for aid in album_ids:
+        album = _client().get_album(aid)
+        album_name_parts.append(album["albumName"])
+        for asset in album["assets"]:
+            if asset["id"] not in all_assets:
+                all_assets[asset["id"]] = asset
+
+    photos = [
+        Photo(id=a["id"], original_filename=a["originalFileName"],
+              local_datetime=a["localDateTime"])
+        for a in sorted(all_assets.values(), key=lambda x: x["localDateTime"])
+    ]
+    for i, p in enumerate(photos):
+        p.order = i
+
+    state = TripState(
+        album_id=primary_id,
+        album_name=", ".join(album_name_parts),
+        grav_trip_slug=grav_trip_slug,
+        photos=photos,
+    )
+    save_state(state, current_app)
+    return redirect(f"/triage?album_id={primary_id}")
+
+
 # TODO(task-6): replace this stub with the real triage route
 @bp.get("/triage")
 def triage():