docs(m3): add the prompt revision interface, seed, and auth gap

UAT requires prompt tuning, so the iteration system is M3; only the editing
UI is deferred.

- METADATA-105 now covers storage, append-only revisions, and recording the
  revision used.
- METADATA-106 adds the REST revision interface (append, activate, read); no
  prompt UI.
- METADATA-107 records the missing authentication as a later row; there is no
  M4 yet, so the PoR carries it.
- PROMPTS.md owns the seed text as revision 0, the seed mechanism, and the
  interface; sections renumbered after inserting them.
- DATA-MODEL.md §7 cites PROMPTS.md, adds content_hash, and states the
  append-only rule.
- task_breakdown.md notes the S7 interface and the deferred auth.

155 requirements; both gates pass.

docs/contracts/PROMPTS.md

@@ -11,22 +11,33 @@ Owns prompt storage, prompt inputs, and the two inference calls.
 | METADATA-35, METADATA-40, METADATA-45, METADATA-50 | Call 1 inputs, constraints, pre-fill, precedence |
 | METADATA-55, METADATA-60, METADATA-65, METADATA-70 | Call 2 output, inputs, dimension safety, inference-off path |
 | METADATA-75, METADATA-80, METADATA-85, METADATA-90, METADATA-95 | non-blocking, deterministic copy, pattern selection, fact block, overlay exclusion |
-| METADATA-100, METADATA-105, METADATA-110, METADATA-115 | feat mapping, prompt storage, button, failure |
+| METADATA-105, METADATA-106, METADATA-107 | prompt storage, revision interface, auth |
 | METADATA-66 | generation logging |
 | SETTINGS-30 | brand voice and geo context |
 | REVIEW-40, REVIEW-50 | editability and field limits |
 
 ## 1. Storage and revisions
 
-- Prompts live in the database, not in text files, with all revisions retained. Tables are in
-  `docs/contracts/DATA-MODEL.md` §7. No prompt files ship with the application; the database is
-  the only prompt source.
-- Each call reads the active revision fresh.
-- Editing a prompt creates a new revision; history is never overwritten.
-- Every generation is logged with its inputs, the request/response when a model was used, and the
-  final stored content.
+- Prompts live in the database, not in text files, with all revisions retained. Storage shape is
+  `docs/contracts/DATA-MODEL.md` §7 (`METADATA-105`).
+- Revisions are append-only. Editing saves a new revision and moves the active pointer; a revision
+  is never updated or deleted. Reset to default and reset to revision are pointer moves.
+- Each call reads the active revision fresh, and the revision used is recorded on the call
+  (`METADATA-66`).
+- The seed text in §6 is read once on first run and written as revision 0 for each call. It is the
+  only prompt content that ships with the application.
 
-## 2. Call 1 — vision classification
+## 2. Revision interface
+
+REST, no UI (`METADATA-106`):
+
+1. `POST /api/v1/prompts/{call}/revisions` appends a revision and returns it.
+2. `POST /api/v1/prompts/{call}/activate` moves the active pointer to a revision.
+3. `GET /api/v1/prompts/{call}` returns the active prompt and the revision list.
+
+The interface is reachable on the trusted network only until it is authenticated (`METADATA-107`).
+
+## 3. Call 1 — vision classification
 
 **When.** Runs automatically after a calibrated draft uploads only when `inference_enabled` is
 true; also on demand or retry. With inference off it is skipped and the fields are filled by hand.
@@ -53,7 +64,7 @@ editable; below it the field stays empty and is not shown as a low-confidence gu
 always win. Call 1 is assist-only and never gates publish. A runtime failure is classified
 recoverable or unrecoverable for the owner.
 
-## 3. Call 2 — content prose
+## 4. Call 2 — content prose
 
 **When.** User-triggered only, via the Generate text control; never automatic. The control appears
 only when content generation is enabled and the endpoint is reachable.
@@ -78,7 +89,7 @@ No provider thread id is used, and Call 1's raw prompt and result are not sent (
 (`METADATA-55`, `METADATA-80`). The primary wood category selects the specialized prompt
 (`METADATA-85`). The owner can edit the result (`REVIEW-40`).
 
-## 4. Fallback and templates
+## 5. Fallback and templates
 
 - With inference off, the server produces the long description so create never lacks prose
   (`METADATA-70`).
@@ -88,8 +99,31 @@ No provider thread id is used, and Call 1's raw prompt and result are not sent (
 - All generated text stays within the field limits in `docs/contracts/WOO-API.md` §9
   (`REVIEW-50`).
 
-## 5. Prompt management
+## 6. Seed prompt text
 
-- The active Call 1 and Call 2 revisions are editable; saving creates a new revision.
+Read once on first run and written as revision 0 for each call (`METADATA-105`). Authored here with
+the rest of the prompt discussion; the seed is the only prompt content that ships with the
+application.
+
+The seed is the starting point for tuning, not a final text. Both calls are revised ad hoc through
+the §2 interface when UAT surfaces a miss.
+
+**`call1` seed.** Classify the slab's species, wood categories, edge type, figure, and grade from
+the supplied photos, choosing only from the supplied synced taxonomy lists, and return the result
+fields in §3 as JSON. Report a confidence for each classified field. Map free-text observations
+(character, inclusions, voids, checks) to the supplied feature-tag list only. Invent no category or
+term.
+
+**`call2` seed.** Write the long product description for the slab from the supplied photos and
+listing facts. The name and short description are already built, so do not repeat them. Use the
+brand voice and geo context given. The dimensions in the fact block are exact: use those strings
+and invent no numbers. Write prose a premium lumber buyer would read.
+
+## 7. Prompt management
+
+- The active Call 1 and Call 2 revisions are editable through the §2 interface; saving creates a
+  new revision.
 - A revision identifies its content, author, and timestamp; `inference_log` records the revision
   used for each call.
+- The revision interface requires authentication before it is exposed beyond the trusted network
+  (`METADATA-107`).