feat(python)!: one filter shape for every service

[JosteinGj]

filter() took three different shapes depending on the entity. Events and datasets wanted an envelope — EventFilterForm(filter=EventFilter(...), limit=100). Timeseries wanted TimeSeriesFilterForm, which despite the name was the criteria, with paging flattened in beside it and no TimeSeriesFilter to nest. Resources took bare keywords and no filter object at all, even though resources.search accepted one. Someone who learned the events API and wrote the obvious analogue for timeseries got a NameError for the class that does not exist and a TypeError for the filter= keyword.

All four now take either the criteria as keywords or a prepared filter= object, with paging always on the call:

client.timeseries.filter(name=["Pump*"], limit=100)

PUMPS = TimeSeriesFilter(name=["Pump*"])
client.timeseries.filter(filter=PUMPS, limit=100, sort_by="name")
client.timeseries.search("vibration", filter=PUMPS)

Passing both a filter and criteria keywords is a TypeError rather than a merge: that call has two intents in it, and either resolution — keyword wins, or union — discards one of them silently.

Keeping paging out of the filter fixes a real defect rather than only tidying names. Because timeseries had no criteria class, timeseries.search accepted the form and reached inside it for the criteria, so every paging field on a form handed to search was discarded without a word — search(q, filter=TimeSeriesFilterForm(name=[...], limit=5), limit=100) silently ignored the 5. A filter that cannot hold a limit cannot lose one, and the same object is now safe to reuse across filter() and search() without carrying a stale cursor into its next use.

TimeSeriesFilterForm, EventFilterForm and DatasetFilterForm are gone from the bindings rather than kept as deprecated aliases. 0.2.0 is a day old with no adoption to protect, and an alias would preserve exactly the ambiguity that caused the bug. Rust is untouched: XFilterForm is the wire body there and stays, which AGENTS.md now states explicitly instead of leaving the Python surface to be inferred from the Rust convention.

Subscriptions are deliberately out of scope: subscriptions.list is a different call with its own contract, and half-converting it would leave a fourth shape rather than removing one.