feat: add TaskCreateMany tool for batch task creation

[danieldisu]

Disclosure

This patch was AI-generated (Claude) at my request, motivated by a noticeable inefficiency when an LLM needs to create several tasks upfront: it was forced to call TaskCreate repeatedly in sequential turns, wasting round-trips and token budget. TaskCreateMany eliminates that by accepting an array in a single call.

QA level: light. Unit tests pass, TypeScript compiles clean, and Biome reports no lint issues.

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Motivation

When an LLM plans a multi-step effort and knows all tasks upfront, calling TaskCreate N times means N sequential tool-use round-trips. This is slow and burns context. A batch primitive is the obvious fix — Claude Code itself ships TaskCreateMany for exactly this reason.

Changes

• src/task-store.ts: Added createMany(items) method — iterates the input array inside a single withLock call, assigns sequential IDs, and returns all created Task objects.
• src/index.ts: Registered TaskCreateMany as Tool 2 (renumbered subsequent tools 3–8). Tool description mirrors Claude Code's spec — includes when-to-use, when-not-to-use, field documentation, and tips. Added TaskCreateMany to TASK_TOOL_NAMES so it resets the reminder interval.
• README.md: Updated tool count (7 → 8), added TaskCreateMany to the tool table with parameter docs and example output.
• test/task-store.test.ts: 6 new unit tests covering sequential IDs, pending status, activeForm/metadata preservation, empty array, single item, and interleaving with create.
• test/subagent-integration.test.ts: 5 new integration tests covering tool registration, multi-task summary output, field preservation, single-task input, and empty-array rejection.

What I actually verified

Check	Result
tsc --noEmit	clean
biome check src/ test/	clean
vitest run	160 passed (5 files)
Manual live session	verified locally

Diffstat: 5 files changed, +290, -9.

[tintinweb]

starting a discussion here: #25 (comment)