Merge reference implementation SDK changes (2026-05-04)

[Copilot]

Resolves #149

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Before the change?

• Java SDK was synced to reference implementation commit e42b726ca42bd1b2e099a956c9287ba9435ba3e5
• No support for copilotHome, tcpConnectionToken, instructionDirectories, continuePendingWork, or MCP OAuth fields

After the change?

Ports 16 commits from github/copilot-sdk (e42b726→c063458).

New client options:

• copilotHome — sets COPILOT_HOME env var on spawned CLI for custom data directory
• tcpConnectionToken — optional connection token for TCP servers; auto-generates UUID when SDK spawns CLI in TCP mode

New session config fields:

• instructionDirectories — additional directories for custom instruction file discovery (create + resume)
• continuePendingWork — on resume, continue pending tool calls/permission prompts from prior suspend

MCP OAuth support:

• oauthClientId, oauthPublicClient, oauthGrantType on McpHttpServerConfig

// New copilotHome + tcpConnectionToken usage
var options = new CopilotClientOptions()
    .setCopilotHome("/custom/data")
    .setUseStdio(false)
    .setTcpConnectionToken("my-token");

// instructionDirectories on session create
var session = client.createSession(
    new SessionConfig()
        .setInstructionDirectories(List.of("/extra/instructions"))
).get();

// continuePendingWork on resume
var resumed = client.resumeSession(id,
    new ResumeSessionConfig()
        .setContinuePendingWork(true)
).get();

Not ported (intentionally):

• 155e887 Replace StreamJsonRpc — Java SDK has its own JSON-RPC impl
• f8cf846 Derive session event envelopes from schema — generated code only
• f7f9450/c063458/ced6613 E2E test expansion — snapshots not yet available at old harness commit
• 6a0e065 Version update logic refinement — internal tooling
• Doc changes — Python-specific or Docker setup not applicable

Pull request checklist

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• mvn spotless:apply has been run to format the code
• mvn clean verify passes locally

Does this introduce a breaking change?

• Yes
• No

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[edburns]

Closing: PR #151 was merged first covering most of this content. The remaining features (continuePendingWork, MCP OAuth, .lastmerge sync to c063458) will be picked up by the next scheduled reference-impl sync.