feat: Add a new backend API for activity feed

[thomass-dev]

Author: Thomas S thomas@probabl.ai
Author: Matt J matthieu@probabl.ai

---

Part of #767 .

[github-actions]

pytest coverage report

File	Stmts	Miss	Cover	Missing
src/skore
__init__.py	18	0	100%
__main__.py	8	1	1	80%
exceptions.py	4	0	100%
src/skore/cli
__init__.py	8	0	100%
cli.py	32	0	100%
launch_dashboard.py	22	12	0	42%
quickstart_command.py	12	2	0	83%
src/skore/item
__init__.py	21	0	100%
cross_validation_item.py	116	5	4	94%
item.py	22	1	0	95%
item_repository.py	42	2	1	93%
media_item.py	60	4	1	93%
numpy_array_item.py	21	1	1	92%
pandas_dataframe_item.py	30	1	1	94%
pandas_series_item.py	30	1	1	94%
polars_dataframe_item.py	28	1	1	94%
polars_series_item.py	23	1	1	93%
primitive_item.py	23	2	1	91%
sklearn_base_estimator_item.py	29	1	1	94%
skrub_table_report_item.py	10	1	1	86%
src/skore/persistence
__init__.py	0	0	100%
abstract_storage.py	22	1	0	95%
disk_cache_storage.py	27	1	1	94%
in_memory_storage.py	20	0	100%
src/skore/project
__init__.py	4	0	100%
create.py	50	8	0	88%
load.py	23	3	0	89%
project.py	63	2	2	95%
src/skore/sklearn
__init__.py	3	0	100%
cross_validate.py	70	4	3	91%
find_ml_task.py	19	2	3	85%
types.py	2	0	100%
src/skore/sklearn/train_test_split
__init__.py	0	0	100%
train_test_split.py	34	1	1	96%
src/skore/sklearn/train_test_split/warning
__init__.py	8	0	100%
high_class_imbalance_too_few_examples_warning.py	17	3	2	78%
high_class_imbalance_warning.py	17	2	1	87%
random_state_unset_warning.py	11	1	1	87%
shuffle_true_warning.py	9	0	1	91%
stratify_is_set_warning.py	11	1	1	87%
time_based_column_warning.py	22	1	2	89%
train_test_split_warning.py	5	1	0	80%
src/skore/ui
__init__.py	0	0	100%
app.py	25	5	2	71%
dependencies.py	7	1	0	86%
project_routes.py	86	5	2	92%
src/skore/utils
__init__.py	0	0	100%
_show_versions.py	29	0	100%
src/skore/view
__init__.py	0	0	100%
view.py	5	0	100%
view_repository.py	16	2	1	83%
TOTAL	1164	80	91%

Tests	Skipped	Failures	Errors	Time
168	0 💤	0 ❌	0 🔥	1m 5s ⏱️