fix(rust): send reward notices, and keep a downed line's credit rule (W21, W4)

W21: the permission push named its fields one by one and left out
`notices`, so no kit reward, lend or give ever told its player
anything (D333). The body is now built by `pushBody`, which carries
every field the payload has; a test fails if a payload field is
dropped again.

W4: a downed patrol helicopter, Chinook or Bradley is stored with the
credit rule in force when it arrived, and the feed reads that stamp.
Before, the line re-credited past rows with the server's current rule
while the Rotorbane/Tankbreaker counts kept the old one. Rows stored
before this change keep today's reading.

PLAN_LAST_FIXES.md stage 1.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

swagger-fragment.json

@@ -3203,7 +3203,7 @@
           "Public · Rust"
         ],
         "summary": "Recent events on one Rust server",
-        "description": "The killfeed and everything else public that happened on a server, newest first. Narrow with `kind` (comma-separated) and `wipe`. Only publicly classified kinds are ever returned — moderation events, login attempts and anything carrying an IP address are stored but never served here. Kinds that name a player who was on the server (connects, respawns, deaths, chat, tallies) are served only to viewers inside the operator’s presence audience, which defaults to staff; `presenceHidden` says when they were withheld. Rust’s own world events (protocol 14, PLAN_REDESIGNS §14.3.1) arrive as `world.event` with `event` naming which of 24: they are public, with a `grid` worked out from the map, but a player’s `name` (and the names in `credited`) only for the presence audience, a Steam id and a position only for staff, and a type this build does not know only for staff. A downed patrol helicopter, Chinook or Bradley carries `credited` and `creditedCount` by the server’s `creditRule`.",
+        "description": "The killfeed and everything else public that happened on a server, newest first. Narrow with `kind` (comma-separated) and `wipe`. Only publicly classified kinds are ever returned — moderation events, login attempts and anything carrying an IP address are stored but never served here. Kinds that name a player who was on the server (connects, respawns, deaths, chat, tallies) are served only to viewers inside the operator’s presence audience, which defaults to staff; `presenceHidden` says when they were withheld. Rust’s own world events (protocol 14, PLAN_REDESIGNS §14.3.1) arrive as `world.event` with `event` naming which of 24: they are public, with a `grid` worked out from the map, but a player’s `name` (and the names in `credited`) only for the presence audience, a Steam id and a position only for staff, and a type this build does not know only for staff. A downed patrol helicopter, Chinook or Bradley carries `credited` and `creditedCount` by the server’s `creditRule` as it was when the event arrived, so a line keeps naming whom the Rotorbane and Tankbreaker counts credited after the rule changes.",
         "parameters": [
           {
             "name": "id",