docs: bump version at deploy time, not per pull request (#112)

Version bumps in feature pull requests kept conflicting on the same version
line. The monorepo deploy skill now makes one bump commit on main per
promotion, then tags and releases it on the deploy merge commit.

Closes #111

Author: dev-yunseong

AGENTS.md

@@ -89,9 +89,13 @@ resources. Test-only fixtures may remain with their tests.
 
 ## Versioning
 
-`version` in `build.gradle` is the lobby server's single version source. Update
-it in every runtime-behavior change: PATCH for backward-compatible fixes and
-internal changes, MINOR for backward-compatible features, and MAJOR for
-breaking API or protocol changes. Do not bump for documentation, tests, or
-agent-instruction-only changes. Never add a second runtime version or use a
-`-SNAPSHOT` deployable version. Spring Boot build info embeds this value.
+`version` in `build.gradle` is the lobby server's single version source.
+Do not bump it in a pull request. The monorepo `deploy` skill bumps it once per
+promotion: it commits `chore(release): WordOnlineMatching vX.Y.Z` to `main`, merges
+`main` into `deploy`, then tags and releases `vX.Y.Z` on the merge commit. The level comes
+from the Conventional Commit messages promoted in that release: MAJOR for a `!`
+marker or a `BREAKING CHANGE` trailer, MINOR for `feat:`, PATCH otherwise, so
+write accurate commit types.
+
+Never add a second runtime version or use a `-SNAPSHOT` deployable version.
+Spring Boot build info embeds this value.