Use idiomatic Effect patterns in diagnostics

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What Changed

• Refactored trace diagnostics NDJSON parsing to use Schema.fromJsonString decoders and Option helpers instead of JSON.parse and null sentinels.
• Refactored process diagnostics to use Duration for query timeout policy, Schema decoding for Windows process JSON, granular tagged errors, and Layer.mock/assert in tests.

Why

These changes make the diagnostics code easier to test and maintain with Effect-native primitives while keeping the existing runtime behavior and service boundaries focused.

UI Changes

Not applicable.

Checklist

• This PR is small and focused
• I explained what changed and why
• I included before/after screenshots for any UI changes
• I included a video for animation/interaction changes

  

Note

Refactor diagnostics to use idiomatic Effect patterns with structured errors and schema decoding

• Replaces a single generic ProcessDiagnosticsError with a tagged union of specific error types (ProcessQueryError, ProcessQueryTimeoutError, ProcessCommandExitError, ProcessSignalRejectedError, ProcessSignalFailedError), each with structured fields.
• Introduces WindowsProcessRowSchema and schema-driven JSON decoding in ProcessDiagnostics.ts, replacing raw JSON.parse; invalid entries are skipped and decode failures return [].
• Reworks TraceDiagnostics.ts to use effect/Schema for trace line decoding and Option-based helpers instead of null-returning utilities.
• Converts PROCESS_QUERY_TIMEOUT_MS from a numeric millisecond constant to a Duration value.
• Behavioral Change: timeout failures now emit ProcessQueryTimeoutError with timeoutMillis; non-zero process exit now emits ProcessCommandExitError with command, exitCode, and stderr.

^{Macroscope summarized bed9031.}