Add experimental TraceTimingMiddleware and refine ASGI header typing in IMiddleware

[cobycloud]

Motivation

• Provide an experimental ASGI middleware that propagates W3C trace-context and emits compact Server-Timing metrics for latency observability.
• Improve typing for ASGI headers in the core middleware interface to allow clearer, reusable header types across middleware implementations.

Description

• Introduces a new experimental package swarmauri_middleware_tracetiming with TraceTimingMiddleware that registers via ComponentBase and implements MiddlewareBase hooks on_scope and on_send.
• TraceTimingMiddleware extracts or generates traceparent/tracestate, stores timing information on the request scope, and writes server-timing, timing-allow-origin, and trace headers on http.response.start; an edge_ms_getter can be injected to include edge duration.
• Adds a small HeaderCollection helper for case-insensitive ASGI header read/write and a _gen_trace_ids() helper to create compliant traceparent values.
• Updates pkgs/pyproject.toml to include the new experimental package and refactors the middleware interface IMiddleware typing by introducing Header: TypeAlias, Headers: TypeAlias, and updating Message.headers to use Headers.

Testing

• Ran package tests for the new middleware with pytest pkgs/experimental/swarmauri_middleware_tracetiming -q, executing unit tests in tests/unit and integration tests in tests/i9n, and all tests passed.
• Verified importability via the integration import test test_import_package which succeeded.

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Codex Task