break(sdk): stop accepting serverPort on device-scoped adb executors

[thymikee]

Purpose

After #2632 an adb request carries its server in the invocation's target, which is the only channel a route can actually run against. AndroidAdbExecutorOptions.serverPort still exists on the same options bag, and several functions exist only to police a field that can never win on the device routes. Removing it from those types makes a mismatch unrepresentable instead of refused.

Current shape

export type AndroidAdbExecutorOptions = {
  allowFailure?: boolean;
  timeoutMs?: number;
  // …
  serverPort?: number; // second channel: ignored on device routes, refused under a lease
};

export type AndroidAdbExecutor = (
  args: string[],
  options?: AndroidAdbExecutorOptions,
) => Promise<AndroidAdbExecutorResult>;

Required behavior

• Device-scoped surfaces — AndroidAdbExecutor, AndroidAdbSpawner, and the *WithAdb helpers exported by agent-device/android-adb — stop declaring serverPort. The port a device route uses stays what it was built with (createLocalAndroidAdbProvider(device, { serverPort }), createDeviceAdbExecutor(device, { serverPort })) or what the active lease owns.
• Host-level adb keeps a per-call port, because there the caller owns the server: runAndroidHostAdb(invocation, { serverPort: 15_038 }). It shares AndroidAdbExecutorOptions with the device routes today, so splitting the two option types is the first step.
• A JavaScript caller that still passes serverPort to a device executor gets the route's own server, as today. No runtime sniffing of an option the type no longer declares; the lease refusal stays where the lease is known.

Observable completion

• serverPort is absent from the options type that agent-device/android-adb publishes (AndroidAdbExecutorOptions, re-exported by src/sdk/android-adb.ts), while the host options type still declares it.
• These stop existing or shrink to one channel each: deviceServerPort's three-way precedence, the serverPort destructuring in createSerialAdbExecutor and createSerialAdbSpawner, the option-channel removal in lowerAndroidAdbInvocation, and the per-call callers of requireSameAndroidAdbServer in execOnScopedTransport.
• Existing lease tests keep passing unchanged: a leased route still refuses a construction port that differs.

Compatibility

Type-level narrowing of an input type in a published surface: code that passes serverPort to a device executor stops compiling, and no released runtime behavior changes for callers who never passed it. The semver call (minor with a changelog note, or wait for the next major) belongs to a maintainer, along with whether to deprecate the field for one release first.

Dependencies

Blocked by: #2632 landing. Not coupled to #2026 (quoting) or the daemon/root closure work in #2545.

Exclusions

No change to lease environment plumbing (ANDROID_ADB_SERVER_PORT lowering), discovery, or provider admission.