feedback2 docs: version 0.1.2 — package.json, package-lock.json, APP_VERSION, README badge and sentences, DEPLOY, CHANGELOG entry

The CHANGELOG 0.1.2 entry covers GitHub #16, #25, #32, #33, #35, #38, #42, #43, #44, #51, #52 and PR #27, #28, #29, #48 (and #40's test case);
#58 / #60 / #64 (DESIGN §22.14–§22.16) are added when their subsections land.

shared/constants.js

@@ -3,7 +3,7 @@
 export const PROTOCOL_VERSION = 1;
 /** Release version shown to players (title screen, server banner, /healthz). Kept equal to package.json "version"
  * (test/version.test.js); PROTOCOL_VERSION above is the separate wire-format number. */
-export const APP_VERSION = '0.1.1';
+export const APP_VERSION = '0.1.2';
 
 export const MAX_SEATS = 4;
 export const ROOM_CODE_LEN = 4;