[Feature] Format Java with AOSP style (4-space indentation) #103

Summary

Spotless formats Java with googleJavaFormat() (build.gradle.kts, the spotless { java { … } } block), set in the MVP commit dd8ef5f. Google Java Style uses 2-space indentation. Switch to AOSP style, which keeps the same formatter but indents with 4 spaces (8 for continuation lines), at the same 100-column limit.

Changes

• build.gradle.kts: googleJavaFormat() becomes googleJavaFormat().aosp().
• Run ./gradlew spotlessApply across the repo, in a commit that contains only the reformat.
• Add that commit's hash to .git-blame-ignore-revs, so git blame and GitHub's blame view skip it. Mention git config blame.ignoreRevsFile .git-blame-ignore-revs in the README's development section.
• Check that the constitution, AGENTS.md and .github/REVIEW_CHECKLIST.md don't describe the old style; update them if they do.

Sequencing

The reformat touches every Java file, so open branches conflict with it. Land it between feature PRs, not in the middle of one. A branch rebases onto it cleanly if it runs spotlessApply with the new config first, so that only real changes remain. Feature 014 (#100) is in progress, so do this before or after #100 merges, not during.

Acceptance

• ./gradlew build is green, with spotlessCheck enforcing AOSP style in the pre-commit hook and CI.
• The reformat commit changes formatting only, plus the one-line config change. Deeper indentation makes some lines wrap differently, so git diff -w won't be empty; the check is that the build and every test still pass with no other source edits.
• .git-blame-ignore-revs lists the reformat commit.