refactor: use context var and init whoami sample

[gao-sun]

• bump python version per MCP SDK latest update
• use ContextVar to store per-request context
• init whoami sample to showcase basic usage

[codecov]

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[Copilot]

Pull Request Overview

This PR refactors exception naming and handling to use token-based terminology, integrates a context variable for storing authentication info, and updates the whoami sample accordingly. Key changes include replacing "JWT" exception names with "Token" exception names across tests and middleware, injecting a ContextVar for auth info in various functions and tests, and adjusting server sample and configuration to align with the new design.

Reviewed Changes

Copilot reviewed 15 out of 16 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/utils/create_verify_jwt_test.py	Updated test assertions and exception names to reflect token verification changes.
tests/middleware/create_bearer_auth_test.py	Refactored tests to inject and use a ContextVar for auth info and updated exception names and error messages.
tests/exceptions_test.py	Replaced JWT exception tests with token exception tests and updated expected messages.
tests/__init__test.py	Adjusted metadata and bearer auth middleware tests to use the new ContextVar parameter.
samples/server/whoami.py	Introduced a whoami tool sample that leverages the new context variable-based auth info.
samples/server/starlette.py	Removed sample file as part of the refactor.
pyproject.toml	Raised the minimum Python version and updated dependency versions.
mcpauth/utils/_create_verify_jwt.py	Replaced JwtPayload usage and exception names, omitting expires_at from AuthInfo creation.
mcpauth/types.py	Updated AuthInfo fields (e.g., making client_id optional, scopes default empty) and added JwtPayload model.
mcpauth/middleware/create_bearer_auth.py	Modified to accept a ContextVar parameter and store auth info via the context variable rather than attaching it to the request state.
mcpauth/exceptions.py	Renamed JWT verification exception to token verification exception and updated descriptions accordingly.
mcpauth/config.py	Added the userinfo_endpoint field to AuthorizationServerMetadata.
mcpauth/init.py	Updated MCPAuth initialization to use the context variable for maintaining auth info.
.github/workflows/main.yml	Updated the Python version matrix.

Files not reviewed (1)

• .python-version: Language not supported