feat(deploy): branch model — box tracks release, dev is WIP-integration [#779 #344]

webhook ref-guard + sha-watch sensor pinned to ?sha=release;
sensor renamed pfv_deploy_gitea_release_head; master frozen.
https://projects.knownelement.com/issues/779

README.md

@@ -134,16 +134,23 @@ apps.
 
 ## 🚀 Deployment pipeline
 
+**Branch model (2026-09-04):** `dev` = WIP integration — the pipeline
+IGNORES it. `release` = what the box runs — pushing release IS the deploy.
+`master` is frozen (pre-branch-model history). A PR process with AI +
+human reviewers will gate dev → release (founder, upcoming).
+
 ```mermaid
 flowchart LR
-    PUSH[📝 git push] --> HOOK[gitea webhook<br/>fast path]
-    PUSH --> SHA[sha-watch<br/>safety net · 300 s poll]
+    PUSH[📝 push to dev] --> NOOP[🚫 pipeline ignores dev]
+    REL[🚀 merge dev → release<br/>and push] --> HOOK[gitea webhook<br/>fast path]
+    REL --> SHA[sha-watch<br/>release sha · 300 s poll]
     HOOK & SHA --> CHECK{changed files?}
-    CHECK -->|packages/**| RESTART[♻️ core restart<br/>webhook triggers need it]
+    CHECK -->|configuration.yaml,<br/>packages/**| RESTART[♻️ core restart<br/>webhook triggers need it]
     CHECK -->|other YAML| RELOAD[⚡ reload only<br/>~5 min to live]
 ```
 
-Gate before pushing `packages/**`: `ha core check` must pass on-box.
+Gate before pushing `release` (and after any `packages/**` change on
+`dev`): `ha core check` must pass on-box.
 Measured end-to-end: 4 m 52 s commit → live.
 
 ## 🗺️ Repo map