fix: call model_dump() on request bodies, not the v1 dict()

[gsneto]

Closes #67.

What changed

taskuary/server.py called pydantic v1's body.dict() in ten places - every request that touched a body logged PydanticDeprecatedSince20, and the method is gone in v3. All ten are model_dump() now.

tests/test_no_pydantic_v1.py is the lock: it reads server.py and fails, naming the line, if a .dict() call comes back.

Why

pyproject.toml requires pydantic>=2. model_dump() is v2's name for the same call and returns the same shape, so no response changes.

How

rg -n "\.dict\(" taskuary/server.py -> ten hits: task create/update, split, calendar prep, ingest push, fixtures, and three settings-style updates. Each is .model_dump().

The guard test is verified against a reintroduced call, not just a green run: with body.dict() planted back at server.py:566 it fails and names the line.

Tests

python -m pytest tests/test_no_pydantic_v1.py -q
1 passed

python -m pytest -q
3 failed, 5362 passed, 8 skipped

The three failures are tests/test_browserview.py - RuntimeError: Event loop is closed in the websockets.serve teardown. They are not from this change: with the change stashed, the same file fails on master.

git stash push -u
python -m pytest tests/test_browserview.py -q
4 failed, 14 passed
git stash pop

Windows 11, Python 3.12.10, websockets 17.1.