Python: refresh dev dependencies and validate runtime bounds (#6238)

Updates third-party dev dependencies across the Python workspace and
validates that all runtime dependency bounds still hold at both ends.

Dev dependency bumps (root, lab, declarative, durabletask):
- uv 0.11.6 -> 0.11.17, ruff 0.15.8 -> 0.15.15,
  pytest-asyncio 1.3.0 -> 1.4.0, mcp 1.27.0 -> 1.27.2,
  azure-monitor-opentelemetry 1.8.7 -> 1.8.8,
  poethepoet 0.42.1 -> 0.46.0, prek 0.3.9 -> 0.4.3,
  types-python-dateutil and types-PyYaml stub bumps.
- Transitive Dependabot items swept via lock: idna 3.11 -> 3.17,
  pip 26.0.1 -> 26.1.2.

Deliberately excluded:
- opentelemetry-sdk stays 1.40.0: azure-monitor-opentelemetry (incl.
  1.8.8) hard-pins opentelemetry-sdk==1.40.
- mypy stays 1.20.0 and pyright stays 1.1.408: the 2.1.0 / 1.1.409
  bumps introduce new diagnostics that fail type checking and need
  dedicated PRs.
- rich kept as a range: agentlightning (lab[lightning]) forces
  rich==13.9.4.

Code/formatting changes driven by the ruff upgrade:
- devui lifespan now uses try/finally so shutdown cleanup always runs
  (ruff RUF075).
- Removed unused TYPE_CHECKING imports in core and foundry flagged by
  ruff 0.15.15.
- Reapplied ruff 0.15.15 formatting to the files it changed.

Validation: validate-dependency-bounds-test "*" passes (31/31 lower +
31/31 upper); typing 62/62; lint 31/31; devui tests pass.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

python/samples/semantic-kernel-migration/orchestrations/sequential.py

@@ -78,12 +78,14 @@ async def sk_agent_response_callback(
 async def run_agent_framework_example(prompt: str) -> list[Message]:
     client = OpenAIChatCompletionClient(credential=AzureCliCredential())
 
-    writer = Agent(client=client,
+    writer = Agent(
+        client=client,
         instructions=("You are a concise copywriter. Provide a single, punchy marketing sentence based on the prompt."),
         name="writer",
     )
 
-    reviewer = Agent(client=client,
+    reviewer = Agent(
+        client=client,
         instructions=("You are a thoughtful reviewer. Give brief feedback on the previous assistant message."),
         name="reviewer",
     )