fix(tests): make the PilotTests target compile and run

[TeoSlayer]

Problem

The PilotTests target did not compile, so swift test was red and 0 tests ran.

Six compile errors, three distinct causes:

1. Non-exhaustive switches over Pilot.Error — .dataTooLarge was added to the enum but three switch statements in the tests were never updated (StartErrorPathTests.swift:84, :135, IntegrationTests.swift:73).
2. testPortTruncationDetection was at file scope, after the closing brace of DatagramTests — XCTest could never have discovered it even if it compiled.
3. Mixed-width NSNumber comparisons — XCTAssertEqual(n.uint16Value, n.uint64Value) binds both arguments to a single generic parameter T, so UInt16 vs UInt64 is a hard error. (The same expression compiles in Pilot.swift only because the stdlib has heterogeneous == for BinaryInteger.)

Changes

• Added the missing .dataTooLarge cases in all three switches; extended ErrorTests to cover its description and case-distinctness.
• Moved testPortTruncationDetection inside DatagramTests and pointed it at the real decode path instead of re-implementing the check inline. Pilot.decodeDatagram(_:) is split out of receive() (which now just calls it) and ports are validated by range-checking a single signed 64-bit value. NSNumber.uint16Value wraps, so 70000 read back as 4464 and -1 as 65535; both are now rejected with .invalidResponse. Added decode tests for missing/mistyped fields and the raw-byte-array / empty-data fallbacks.
• Added internal Pilot.attach(driverHandle:start:) so MockDaemonTests can drive the public send() / receive() wrapper over the mock daemon's SendTo→RecvFrom loopback, not just the raw C symbols. stop() now tears down the embedded daemon only for instances that started it. New testWrapperSendReceiveRoundtrip actually calls receive() and asserts the round-tripped payload and ports.
• Build the mock daemon with GOWORK=off. It is a nested Go module, and a go.work higher up the tree made go build fail with "main module does not contain package …", which silently skipped all 14 MockDaemonTests.

Verification

swift build   # Build complete
swift test    # Executed 49 tests, with 6 tests skipped and 0 failures

The 6 skips are the opt-in daemon-backed tests that require PILOT_INTEGRATION=1 and a reachable registry. All 14 MockDaemonTests now run (previously all skipped).

🤖 Generated with Claude Code