refactor(tests): overhaul visual tests — single server, mock emails, fix init_db

- Consolidate 3 duplicate server processes into 1 session-scoped
  live_server fixture in conftest.py (port 5111, shared across all
  visual test modules). Reduces startup overhead from ~3× to 1×.

- Fix init_db mock: patch padelnomics.app.init_db (where it's used)
  instead of core.init_db (where it's defined). The before_serving
  hook imported init_db locally — patching core alone didn't prevent
  the real init_db from replacing the in-memory test DB.

- Keep patches active through app.run_task() so before_serving hooks
  can't replace the test DB during the server's lifetime.

- Force RESEND_API_KEY="" in the visual test server subprocess to
  prevent real email sends (dev mode: prints to stdout, returns "dev").

- Remove 4 screenshot-only no-op tests, replace with single
  test_capture_screenshots that grabs all pages in one pass.

- Fix test_planner_tab_switching: remove nonexistent "metrics" tab.

- Delete ~200 lines of duplicated boilerplate from 3 test files.

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

web/tests/conftest.py

@@ -218,3 +218,86 @@ def sign_payload(payload_bytes: bytes, secret: str = "whsec_test_secret") -> str
     data = f"{ts}:{payload_bytes.decode()}".encode()
     h1 = hmac.new(secret.encode(), data, hashlib.sha256).hexdigest()
     return f"ts={ts};h1={h1}"
+
+
+# ── Visual test fixtures (Playwright) ────────────────────────
+# Session-scoped: one server + one browser for all visual tests.
+
+_VISUAL_PORT = 5111
+
+
+def _run_visual_server(ready_event):
+    """Run a Quart dev server in a subprocess for visual/E2E tests.
+
+    Forces RESEND_API_KEY="" so no real emails are sent.
+    Runs migrations in-process to build the full schema (including FTS tables).
+    """
+    import asyncio
+    import os
+
+    os.environ["RESEND_API_KEY"] = ""
+
+    async def _serve():
+        # Build schema DDL in-process (FTS5 virtual tables need this)
+        tmp_db = str(Path(tempfile.mkdtemp()) / "schema.db")
+        migrate(tmp_db)
+        tmp_conn = sqlite3.connect(tmp_db)
+        rows = tmp_conn.execute(
+            "SELECT sql FROM sqlite_master"
+            " WHERE sql IS NOT NULL"
+            " AND name NOT LIKE 'sqlite_%'"
+            " AND name NOT LIKE '%_fts_%'"
+            " AND name != '_migrations'"
+            " ORDER BY rowid"
+        ).fetchall()
+        tmp_conn.close()
+        schema_ddl = ";\n".join(r[0] for r in rows) + ";"
+
+        conn = await aiosqlite.connect(":memory:")
+        conn.row_factory = aiosqlite.Row
+        await conn.execute("PRAGMA foreign_keys=ON")
+        await conn.executescript(schema_ddl)
+        await conn.commit()
+        core._db = conn
+
+        # Patch init_db/close_db where they're USED (app.py imports them
+        # locally via `from .core import init_db` — patching core.init_db
+        # alone doesn't affect the local binding in app.py).
+        # Patches must stay active through run_task() because before_serving
+        # hooks call init_db() which would replace our in-memory DB.
+        with patch("padelnomics.app.init_db", new_callable=AsyncMock), \
+             patch("padelnomics.app.close_db", new_callable=AsyncMock):
+            app = create_app()
+            app.config["TESTING"] = True
+            ready_event.set()
+            await app.run_task(host="127.0.0.1", port=_VISUAL_PORT)
+
+    asyncio.run(_serve())
+
+
+@pytest.fixture(scope="session")
+def live_server():
+    """Start a live Quart server on port 5111 for all visual/E2E tests."""
+    import multiprocessing
+
+    ready = multiprocessing.Event()
+    proc = multiprocessing.Process(
+        target=_run_visual_server, args=(ready,), daemon=True
+    )
+    proc.start()
+    ready.wait(timeout=10)
+    time.sleep(1)
+    yield f"http://127.0.0.1:{_VISUAL_PORT}"
+    proc.terminate()
+    proc.join(timeout=5)
+
+
+@pytest.fixture(scope="session")
+def browser():
+    """Launch a headless Chromium browser (once per test session)."""
+    from playwright.sync_api import sync_playwright
+
+    with sync_playwright() as p:
+        b = p.chromium.launch(headless=True)
+        yield b
+        b.close()