docs(schema): document milestone slot and milestone_fieldtest phase

Correct the cycle vocabulary description, add the milestone container
slot, fix the minimal-profile example, and document the
milestone_fieldtest phase that gates the milestone close.

docs/profile-schema.md

@@ -127,8 +127,9 @@ as with other omitted optional features.
 
 | Key            | Type   | Default        | Description |
 |----------------|--------|----------------|-------------|
-| `cycle`        | string | `cycle`        | What a top-level work unit is called. Examples: `milestone`, `release`, `epic`. |
-| `subcycle`     | string | `iteration`    | What a sub-unit is called. Examples: `iteration`, `sprint`, `story`. |
+| `cycle`        | string | `cycle`        | One round in the pipeline graph (NOT the top-level container). Examples: `cycle`, `release`, `epic`. |
+| `subcycle`     | string | `iteration`    | A sub-unit of a cycle. Examples: `iteration`, `sprint`, `story`. |
+| `milestone`    | string | `milestone`    | Tracker container spanning many cycles; closes only when complete AND functional (see `pipeline.md` § Milestone-close gate). Examples: `milestone`, `epic`, `release`. |
 | `ledger_entry` | string | `contract`     | What a single design-ledger entry is called. Examples: `contract`, `RFC`, `ADR`. |
 
 Skills use these names in their generated artefacts and prose.
@@ -184,6 +185,10 @@ pipeline:
   fieldtest:
     boss_only: true               # only orchestrator dispatches
     when: surface_touch           # condition tag (orchestrator judgement)
+  milestone_fieldtest:
+    boss_only: true
+    when: surface_touch           # end-to-end proof of the milestone's promise
+    gates_close: milestone        # its green roll-up is the functional leg of the milestone-close gate
   docwriter:
     boss_only: true
     when: api_stable_across_n_cycles
@@ -210,7 +215,7 @@ commands:
   test: cargo test
 
 vocabulary:
-  cycle: milestone
+  cycle: cycle
   subcycle: iteration
 
 standing_reading: