v0.7.2: release — TDD

All 14 v0.7.2 items wired, tested, and documented.

Release checklist:
- ROADMAP: all 14 items marked DONE
- README: version badge v0.7.1 → v0.7.2
- CHANGELOG: v0.7.2 entry with feature summaries
- core-transport: make-hello-message 0.7.1 → 0.7.2
- .env.example: TAG_CATEGORIES, SELF_BUILD_MODE
- /help list: all 16 commands documented

Phase 1 (wire deferred):
- call-with-tool-timeout in action-tool-execute
- dispatcher-privacy-severity in dispatcher-check
- Ctrl+G gate-trace toggle, Ctrl+F search placeholder

Phase 2 (finish features):
- /audit verify, /resume <n>, /help <topic>

Core: 88/88  TUI Main: 85/86 (1 pre-existing flake)

lisp/core-transport.lisp

@@ -62,7 +62,7 @@
   (let ((stream (usocket:socket-stream socket)))
     (handler-case
         (progn
-          (format stream "~a" (frame-message (make-hello-message "0.7.1")))
+          (format stream "~a" (frame-message (make-hello-message "0.7.2")))
           (finish-output stream)
           (loop
             (let ((msg (read-framed-message stream)))