feat(#2659): serve hive-matrix-mcp over persistent streamable-http, drop stdio bridge

docs/persistence.md

@@ -234,7 +234,7 @@ Under `/var/lib/hyperhive/agents/<name>/`:
     hourly and deletes terminal task trios older than 48 hours;
     non-terminal (still-running) tasks are never deleted by vacuum.
   - `hyperhive-todos.sqlite` — loose-ends-v2 todo store. In-container
-    MCP daemons (`hive-bash-daemon`, `hive-matrix-mcp`) and `forge_notify`
+    MCP daemons (`hive-bash-daemon`, `hive-matrix-daemon`) and `forge_notify`
     upsert keyed todos here over the harness's in-agent socket
     (`HIVE_AGENT_SOCKET`); the harness merges them into `get_loose_ends`
     output and clears a row on `mark_todo_done`. Replaced the old
@@ -400,18 +400,13 @@ the body + marker check at that point.
 ## Matrix per-agent daemon + token-arrival trigger
 
 `hive-matrix-daemon` is a long-running matrix-sdk Client + sync
-process per agent. Holds the unix socket the stdio
-`hive-matrix-mcp` bridge talks to, emits hyperhive wake signals
+process per agent. Serves its MCP tools directly over
+streamable-http (`hyperhive.mcp.matrixHttpPort`, no stdio bridge —
+same shape as `hive-bash-daemon`), emits hyperhive wake signals
 on incoming room events via `/run/hive/mcp.sock`. Conditional on
 `hyperhive.matrix.enable` (which both the daemon AND the
 auto-injected `extraMcpServers.matrix` entry read).
 
-Socket path lives inside the systemd-managed runtime dir
-(`RuntimeDirectory = "hive-matrix"` → `/run/hive-matrix/`, owned by
-the agent user) so the daemon can bind without needing root over
-`/run/` itself. Both daemon + bridge agree on the path via the
-`HIVE_MATRIX_SOCKET` env var.
-
 **First-boot ordering**: hive-c0re provisions the matrix token AFTER
 agent containers come up. Without the path-trigger sibling
 (`systemd.paths.hive-matrix-daemon`, `PathExistsGlob =