Bun parity: abort TLS fetches on timeout deadlines

Port js/web/fetch/fetch-tls-abortsignal-timeout.test.ts from the copied Bun corpus.

Required behavior:

• make AbortSignal.timeout deadlines participate in the Home event-loop bridge
• reject TLS fetch and response-body chains before the delayed server response
• preserve TimeoutError identity for 0, 1, 10, 20, 100, and 300 ms deadlines
• attach structured operation, phase, deadline, cause, and composed stack context to timeout reasons
• clean timer/listener state deterministically and add a permanent focused regression
• advance corpus position 4146 with zero failures or unsupported tests

Tracked under #66.

Completed in f762359 and pushed directly to main.

Implemented:

• AbortSignal.timeout routed through the Home timer and virtual-deadline bridge
• TLS fetch timeout dispatch ordered ahead of microtask-backed delayed server responses
• exact virtual deadline accounting for timing assertions
• TimeoutError reasons with ERR_ABORT_TIMEOUT context, operation abort.signal.timeout, deadline phase, timeout value, cause, and composed stack
• permanent focused regression for all six upstream deadlines

Validation:

• indexed Bun corpus position 4146: 6 passed, 0 failed, 0 todo, 0 unsupported
• focused TLS timeout regression: passed
• positions 4144 and 4145 independently green: 4 todo and 4 passed respectively
• zig build --cache-dir /private/tmp/home-zig-abi-cache: passed