profile: add milestone vocabulary slot and milestone_fieldtest phase

Correct the cycle comment (a cycle is a pipeline round, not the
top-level container); add the milestone tracker-container slot and a
commented milestone_fieldtest phase that gates the milestone close.

templates/project-profile.yml

@@ -38,8 +38,9 @@ commands:
 #       cmd: "ail check {file}"
 
 vocabulary:
-  cycle: cycle                            # what a top-level work unit is called
-  subcycle: iteration                     # what a sub-unit is called
+  cycle: cycle                            # one round in the pipeline graph (NOT the top-level container)
+  subcycle: iteration                     # a sub-unit of a cycle
+  milestone: milestone                    # tracker container spanning many cycles; closes only when complete AND functional
   ledger_entry: contract                  # what one design-ledger entry is called
 
 standing_reading:
@@ -70,5 +71,6 @@ pipeline:
   audit:      { mandatory_at: cycle_close }
   debug:      { trigger: bug, red_first: true }
   # boss:      { user_invoked: true }     # autonomous orchestrator mode, /boss
-  # fieldtest: { boss_only: true, when: surface_touch }
+  # fieldtest:           { boss_only: true, when: surface_touch }   # per-cycle usability test
+  # milestone_fieldtest: { boss_only: true, when: surface_touch, gates_close: milestone }  # closing gate: end-to-end proof of the milestone's promise
   # docwriter: { boss_only: true, when: api_stable_across_n_cycles }