docs(sdk): invoke tools by address, not id

[The-AarushiSingh]

Why

Tool in packages/core/sdk/src/tool.ts has address (ToolAddress) and no id.
The SDK README called executor.tools.invoke(target.id, ...).

Change

packages/core/sdk/README.md: both invoke examples now use target.address.

Plugin README address strings were already correct. Docs only.

[devin-ai-integration]

Verdict: mergeable. Docs-only, open ~1 day, applies cleanly on current main.

Verified the claim: Tool in packages/core/sdk/src/tool.ts exposes address: ToolAddress and has no id, so the old executor.tools.invoke(target.id, …) examples in packages/core/sdk/README.md would fail to typecheck for anyone copying them. The plugin READMEs already pass address strings, so this brings the SDK README in line.

Ran on the PR branch: bun run format:check — clean. No code changes, so lint/typecheck/tests are unaffected (CI is green). No changeset needed for a README-only change. Nothing pushed.