dashboard: remove the flow page and the endpoints only it used

The flow page showed the raw broker message stream and had a compose box.
This removes the page and its bundle, its link in the pages menu, and the
styles only it used.

The history endpoint that backfilled it and the operator-send endpoint
behind the compose box had no other caller, so they go too, along with
the broker query behind the history endpoint. The stream endpoint stays:
the dashboard tabs still subscribe to it.

The docs lose the FL0W section and the references to the two endpoints.

docs/web-ui/dashboard.md

@@ -12,21 +12,21 @@ hive-c0re serves the dashboard at `/`.
 It has a fixed chrome header at the top and a `<main>` that shows exactly
 one tab pane at a time. The URL hash (`#agents`, `#rebuild`, `#meta`,
 `#buildlogs`, `#kept`) drives which pane is
-active; hash changes don't reload the page. FL0W and ST4TS
-are standalone pages reached from the pages menu, not from the
+active; hash changes don't reload the page. ST4TS
+is a standalone page reached from the pages menu, not from the
 dashboard tab strip.
 
 **Chrome header** (fixed, overlays the active tab pane):
 - **Pages menu**: a `☰` button at the left of the chrome (`links-menu.js`)
-  opening a popover with links to **flow** (`/flow.html`), **stats**
+  opening a popover with links to **stats**
   (`/stats.html`), **api docs** (`/api/docs/`) and **swarm** (the swarm
   UI at the swarm apex domain, opened in a new tab). The swarm entry
   comes from `state.swarm_public_url`, which hive-c0re reads from
   `HIVE_SWARM_PUBLIC_URL` (set from `services.hyperhive.swarm.domain`);
   with no domain set there is no swarm entry. The standalone pages link back to `/`.
 - **Tab strip**: `◆ 4G3NTS ◆`, `◆ R3BU1LD QU3U3 ◆`, `◆ M3T4 1NPUTS ◆`,
-  `◆ BUILD L0GS ◆`, `◆ K3PT ST4T3 ◆`. In-page tabs only — FL0W / ST4TS
-  live on their own pages, reached from the pages menu. Count pills on
+  `◆ BUILD L0GS ◆`, `◆ K3PT ST4T3 ◆`. In-page tabs only — ST4TS
+  lives on its own page, reached from the pages menu. Count pills on
   4G3NTS (stale containers), R3BU1LD QU3U3 (rebuilds in flight) and
   K3PT ST4T3 (kept-state entries).
 - **Banner-thin** (`░▒▓█▓▒░ HYPERHIVE / HIVE-C0RE / WE ARE THE WIRED ░▒▓█▓▒░`)
@@ -46,10 +46,6 @@ dashboard tab strip.
   to `<swarm> / <hive> // h1ve-c0re` once `hive_name` / `swarm_name`
   arrive in the state snapshot.
 
-The FL0W page uses a slim header (a `← dashboard` back-link + the page
-title) rather than the dashboard tab strip — it's a standalone surface,
-not a tab pane.
-
 ## 4G3NTS tab
 
 **C0NTAINERS** — live containers as a flat list, one row per
@@ -212,7 +208,7 @@ entry with that id pre-expanded.
 Hive-wide turn statistics, aggregated across every agent's
 `hyperhive-turn-stats.sqlite` for the selected window. Not a dashboard
 tab — a standalone page reached from the dashboard's pages menu,
-same minimal chrome as `/flow.html`. Distinct from
+minimal chrome (a back-link and a title). Distinct from
 each agent's own `/stats` page (which carries the per-agent trend
 charts): ST4TS is the swarm-level rollup.
 
@@ -249,42 +245,6 @@ the model id, longest match wins) mapping to
 `{ input, output, cache_read, cache_write }` USD-per-million-token
 prices. Models not covered fall back to hive-c0re's built-in estimate.
 
-## FL0W page (`/flow.html`)
-
-A dedicated full-page terminal (not a tab pane — a separate HTML
-page). Slim chrome: a `← dashboard` back-link, the FL0W
-title, and the agent-filter select (see below). No dashboard tab
-strip — FL0W is a standalone surface reached from the pages menu.
-
-**MESS4GE FL0W** — live broker tail wrapped in a `.terminal-wrap`.
-Cold load backfills the last ~200 messages from `/api/dashboard/history`;
-live frames arrive on `/api/dashboard/stream`. Each row is one broker
-event — `sent` or `delivered` — with `from → to: body`. When a `sent`
-and `delivered` event for the same message arrive within 3 seconds
-(immediate delivery to a live recipient), the page upgrades the row in
-place (arrow becomes green ✓, title reads "sent + delivered") instead of
-rendering two near-identical lines — genuine delivery latency (recipient
-was busy) still appears as a second row. Each row carries `data-from` /
-`data-to` attributes; an **agent filter select in the FL0W header** narrows
-the timeline to messages involving the chosen agent (matched on `from` OR
-`to`), with non-matching rows hidden (`.flow-hidden` class). The selection
-persists in localStorage across reloads; new rows pick up the active filter
-at render time. The dropdown populates from the live container list and
-stays current on add/remove; a saved selection survives even if that agent
-isn't currently listed.
-
-The row is a `flex-wrap: wrap` container holding ts / arrow / from / sep
-/ to chips inline; the **body wraps to its own full-width line below** the
-chips (`flex: 1 1 100%`) so long timestamps and agent names never push the
-body into a narrow trailing column. `min-width: 0` keeps
-`word-break: break-word` effective so the body doesn't force the row wider
-than its container. Sticky-bottom autoscroll + "↓ N new" pill. Below the
-stream sits a terminal-style compose box: `@name` picks the recipient
-(sticky via localStorage; autocomplete from the live container list,
-Tab/Enter to confirm; `@*` broadcasts). `POST /api/op-send` drops
-`{from:"operator", to, body}` into the broker; the resulting SSE frame
-re-renders the terminal row. The operator addresses the root agent as `@root`.
-
 ## Container row
 
 A full-height **square agent icon** (5em, capped) on the left. The
@@ -577,11 +537,6 @@ below — some endpoints aren't in it yet.
   not yet delivered and sets `acked_at = now`. Returns
   `{ "marked": N }`. Agent name validated against
   `[a-z0-9_-]`, 1-63 chars; 400 on bad input.
-- `POST /api/op-send` (`to=<name>`, `body=<text>`) — drop an
-  operator-authored message into `<name>`'s inbox. `to=*` fans
-  out to every registered agent. Returns 200; the broker
-  `Sent` event re-renders the message-flow terminal without a
-  snapshot refetch. Used by the compose textbox under MESS4GE FL0W.
 - `GET /api/build-logs/{agent}?limit=N` — most-recent build log
   headers for one agent, newest first. Returns
   `Vec<BuildLogHeader>` (JSON): `id`, `agent`, `kind`, `cmdline`,
@@ -621,8 +576,7 @@ below — some endpoints aren't in it yet.
   The client trusts that list and linkifies only those tokens,
   so directories, missing files, and forbidden subtrees never
   become anchors. No probe endpoint, no client-side regex
-  heuristics. Historical messages get the same treatment on
-  `/api/dashboard/history` backfill.
+  heuristics.
 - `GET /api/reminders` — list pending reminders for the
   dashboard's queued-reminders panel.
 - `GET /api/stats-hive?window=<1h|4h|24h|3d|7d|30d|all>` — hive-wide
@@ -639,9 +593,6 @@ below — some endpoints aren't in it yet.
 - `GET /api/dashboard/stream` — unified live event channel:
   broker `sent` / `delivered`, plus the mutation events listed
   below. Each frame carries `seq`.
-- `GET /api/dashboard/history` — last ~200 broker messages
-  (wrapped as `{ seq, events }`) for the message-flow
-  terminal's backfill on page load.
   <!-- vale write-good.Passive = YES -->
 
 ## Dashboard event channel
@@ -652,9 +603,7 @@ payload):
 - `sent` / `delivered` — broker traffic, mirrored from the
   intra-process channel by a forwarder task. Both carry `id: i64`
   (the broker row id) and `in_reply_to: Option<i64>` for thread
-  rendering. The dashboard message-flow terminal renders reply
-  rows with a `↳ reply` tag that scroll-highlights the parent
-  row on selection. Used by the message-flow terminal renderer.
+  rendering.
 - `transient_set` (name, transient_kind, since_unix) /
   `transient_cleared` (name) — lifecycle action spinners. The
   client ticks the elapsed-seconds badge off `since_unix`
@@ -696,7 +645,7 @@ payload):
 forms that mutate non-event-derived state** (PURG3 +
 meta-update, since tombstones + meta_inputs aren't event-
 shaped yet). Every other section — transients,
-containers, message flow —
+containers —
 derives from `/api/dashboard/stream` after the initial snapshot,
 maintaining its own client-side store and applying events on
 top.