Add .worktreeinclude for claude --worktree dep inheritance

[kderholtvisma]

Summary

• Adds .worktreeinclude so claude --worktree and subagent worktrees copy the gitignored files they need to build and run.
• Includes node_modules/ and vendor/ so worktrees inherit installed deps from the main repo instead of re-installing per worktree.
• Also lists the standard .env* patterns as a safety net; none are gitignored in this repo today, but the patterns are no-ops if unused.

Test plan

• claude --worktree produces a worktree where node_modules/ is present without running deno/npm install.
• Pre-push gates still pass on this branch: deno fmt --check && deno lint && deno check main.ts && deno test --allow-net.