feat: prune SDK to API-key surface, add stats/usage/metrics/events

Strip session-only routes (auth, me, teams, hosts, channels, admin,
audit-logs) from api/openapi.yaml via new scripts/prune_openapi.py,
which is wired into `make generate` and `make prune-spec`. Spec drops
from 4787 to 1717 lines; regenerated _generated.py drops from 906 to
415 lines with all obsolete models removed.

Add SDK methods on CapsulesResource / AsyncCapsulesResource for the
apiKey-usable routes that were previously unwrapped:
  - capsules.stats(range=...)         -> CapsuleStats
  - capsules.usage(from_=..., to=...) -> UsageResponse (accepts date)
  - capsules.metrics(id, range=...)   -> CapsuleMetrics

Add EventsResource / AsyncEventsResource exposing
WrennClient.events.stream() over /v1/events/stream (SSE). Parser
handles `:keepalive` comments and multi-line `data:` frames.

Re-export new models (CapsuleStats, CapsuleMetrics, MetricPoint,
UsageResponse, SSEEvent, Resource, Actor) from wrenn.models.

Drop email-validator runtime dep (no EmailStr remains). Bump version
to 0.3.0 (pyproject + __version__). Add pyyaml to dev deps and
types-PyYAML to the pre-commit mypy hook for the prune script.

Normalize docstrings on new methods/classes to Google style with
Example:: blocks where useful. Regenerate docs/reference.md.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "wrenn"
-version = "0.2.0"
+version = "0.3.0"
 description = "Python SDK for Wrenn"
 readme = "README.md"
 license = "MIT"
@@ -23,7 +23,6 @@ classifiers = [
 ]
 dependencies = [
     "certifi>=2026.2.25",
-    "email-validator>=2.3.0",
     "httpx>=0.28.1",
     "httpx-ws>=0.9.0",
     "pydantic>=2.12.5",
@@ -41,6 +40,7 @@ dev = [
     "pydoc-markdown>=4.8.2",
     "pytest>=9.0.3",
     "pytest-asyncio>=1.3.0",
+    "pyyaml>=6.0.3",
     "respx>=0.23.1",
     "ruff>=0.15.10",
 ]