Give package.json the MIT license field (closes #76)

`package.json` now carries `"license": "MIT"`, matching `LICENSE`. Without it yarn printed `warning package.json: No license field` and `warning No license field` each time `script/bootstrap` ran inside the Docker phases of `make check`. No other yarn warning appears in the bootstrap output.

Model: opus-5-5

TODO.md

@@ -21,6 +21,9 @@ fmt-check, and commit.
 
 # Completed Steps
 
+- 2026-10-04: `package.json` now has `"license": "MIT"`, matching `LICENSE`, so
+  yarn no longer prints "No license field" when `script/bootstrap` runs it
+  inside the Docker phases (issue 76). That was the only yarn warning there.
 - 2026-10-04: `REPO_POLICIES.md` now states that guidance for coding agents
   lives in one `AGENTS.md` at the repository root, never under a file or
   directory named after one agent tool and never in separate memory files (issue

package.json

@@ -1,4 +1,5 @@
 {
+  "license": "MIT",
   "devDependencies": {
     "prettier": "3.8.1"
   }