feat(inter-tool-launch): implement Inter-Tool Launch Context (Issue #161)

[Copilot]

• Use a meaningful title for the pull request.
• Follow the guidelines from the CONTRIBUTING.md.
• Mention the bug or the feature number the PR will be targeting. — [Feature]: Develop process for tools to talk to each other (CSP?) #161
• Test the change in your own code. (Compile and run)
• Resolve all GH Copilot comments.

---

• Create .github/plans/plan-inter-tool-launch-context.md following the repo plan template
• Part 1 — pptb.config.json schema: pptbConfig.d.ts, validate.js, pptb-validate.js
• Part 2 — IPC Channels: LAUNCH_WITH_CONTEXT, RETURN_INVOCATION_DATA
• Part 3 — Main process: pendingInvocations map, launchToolWithContext, resolveInvocation, null-resolve on premature close
• Part 4 — Tool Preload Bridge: toolboxAPI.invocation namespace (getLaunchContext, returnData, launchTool)
• Part 5 — Renderer: LaunchToolOptions extended, launchToolWithContext routing, preload.ts exposure
• Part 6 — Public types: InvocationAPI in packages/toolboxAPI.d.ts, launchToolWithContext in api.ts
• Part 7 — Documentation: packages/README.md inter-tool section + API reference
• Execution log, code reviewer fixes (empty-object guard, blank line, .gitignore), security scan results, files-changed table, validation steps, risks all documented
• Renamed PptbConfig → PPTBConfig and validatePptbConfig → validatePPTBConfig across packages/pptbConfig.d.ts, packages/lib/validate.js, packages/bin/pptb-validate.js, and the plan file for consistent PPTB casing

[Power-Maverick]

@copilot rename PptbConfig to PPTBConfig, validatePptbConfig to validatePPTBConfig. Also update the copilot instructions plus agents for word "PPTB"; it should either be "PPTB" or "pptb" cannot be mix of upper and lower casing

[Copilot]

@copilot rename PptbConfig to PPTBConfig, validatePptbConfig to validatePPTBConfig. Also update the copilot instructions plus agents for word "PPTB"; it should either be "PPT...

Done in cfd03dc. Renamed PptbConfig → PPTBConfig and validatePptbConfig → validatePPTBConfig across packages/pptbConfig.d.ts, packages/lib/validate.js, packages/bin/pptb-validate.js, and the plan file.

Regarding copilot instructions and agents: no mixed-casing of "PPTB" was found in .github/copilot-instructions.md or any of the agent files — they either use the full uppercase PPTB or the lowercase pptb (as a filename prefix like pptb.config.json or pptb-validate). Let me know if there's a specific file or agent where you spotted the issue.