feat(#2050): set matrix avatar in the daemon over the live client

docs/conventions.md

@@ -474,10 +474,10 @@ the state dir at provisioning time:
 - `forge-avatar-sync` — uploads `hyperhive.icon` SVG to the
   agent's Forgejo profile, so the icon shows up on commits / PRs /
   issue comments.
-- `matrix-avatar-sync` — same idea for matrix profile avatars
-  (two-step `media upload` → `set avatar_url` dance — see
-  `docs/persistence.md::matrix-avatar-sync` for the protocol
-  detail).
+
+(The matrix profile avatar is **not** a oneshot — `hive-matrix-daemon`
+sets it over its live authenticated Client; see
+`docs/persistence.md::matrix avatar`.)
 
 Shape contract — every one of these:
 
@@ -498,7 +498,7 @@ Shape contract — every one of these:
 5. **Re-runnable**: a second invocation produces the same final
    state (idempotent uploads, idempotent config rewrites). Used
    by the `.path` watchers that re-fire on token appearance (see
-   `docs/persistence.md::matrix-avatar-sync`).
+   `docs/persistence.md::Matrix per-agent daemon`).
 
 The artefact lives under the agent user's home where applicable
 (`~/.config/tea/config.yml`) and is chown'd to that user, but the