docs(#727): split docs/web-ui.md into shape / dashboard / agent

docs/web-ui.md (1315 lines) split into three sub-files:
- docs/web-ui/shape.md   — shared SPA skeleton, SSE multiplexing,
  Worker-death self-heal, terminal pane, listener bind, relative
  paths, atomic repaint, side panel
- docs/web-ui/dashboard.md — SW4RM/Y3R/SYST3M/SCH3DUL3S/S3TT1NGS
  tabs, container row, topology tree, selection bar, approval card,
  dashboard endpoints + event channel
- docs/web-ui/agent.md   — header, terminal, composer, inbox, live
  view, slash commands, per-agent endpoints, stats page

docs/web-ui.md replaced with a thin index linking all three.

Section anchors in docs (gateway.md, gotchas.md), Rust doc comments
(hive-ag3nt/src/web_ui.rs), and nix/templates/weston-vnc.nix updated
to point at the correct sub-file. README and CLAUDE.md file-map
updated with sub-file links. Inline // comments in frontend source
left unchanged (they reference the index which redirects to the right
sub-file).

hive-ag3nt/src/web_ui.rs

@@ -80,7 +80,7 @@ pub type Flavor = mcp::Flavor;
 ///
 /// `HIVE_WEB_SOCKET` opt-in selects unix-socket vs TCP binding; the
 /// dual-mode transition + gateway-side consumer live in
-/// [`docs/web-ui.md::Listener bind`](../../../docs/web-ui.md) and
+/// [`docs/web-ui/shape.md::Listener bind`](../../../docs/web-ui/shape.md) and
 /// [`docs/gateway.md::Per-agent unix-socket upstream`](../../../docs/gateway.md).
 ///
 /// # Errors
@@ -219,7 +219,7 @@ fn bind_unix(path: &Path) -> Result<tokio::net::UnixListener> {
 /// a long-held stale socket doesn't flood the journal.
 ///
 /// Uncapped retry + dashboard-banner-on-real-collision rationale:
-/// see [`docs/web-ui.md::Listener bind`](../../../docs/web-ui.md).
+/// see [`docs/web-ui/shape.md::Listener bind`](../../../docs/web-ui/shape.md).
 async fn bind_with_retry(addr: SocketAddr, label: &str) -> Result<tokio::net::TcpListener> {
     let mut delay_ms = 250u64;
     let mut attempts = 0u32;
@@ -433,7 +433,7 @@ struct StateSnapshot {
     /// dashboard card's icon-only nav strip via hive-c0re's
     /// `GET /api/agent/{name}/links` same-origin passthrough proxy
     /// — single source of truth, no CORS. Per-agent page also reads
-    /// this directly. See [`docs/web-ui.md::Container row`] for the
+    /// this directly. See [`docs/web-ui/dashboard.md::Container row`] for the
     /// frontend resolver + which links appear in which conditions.
     links: Vec<AgentLink>,
     /// Human name of this hive instance (e.g. `"pr1ma"`). Sourced
@@ -595,7 +595,7 @@ async fn api_state(State(state): State<AppState>) -> axum::Json<StateSnapshot> {
 /// for `External`; the frontend resolves each against its `kind`
 /// against the right base so the backend never has to guess the
 /// operator's browser host. See
-/// [`docs/web-ui.md::Container row`](../../../docs/web-ui.md) for
+/// [`docs/web-ui/dashboard.md::Container row`](../../../docs/web-ui/dashboard.md) for
 /// the resolver + how `deployed:<sha>` ships alongside.
 fn agent_links(label: &str, gui_enabled: bool) -> Vec<AgentLink> {
     let mut links = Vec::new();
@@ -950,7 +950,7 @@ async fn post_new_session(State(state): State<AppState>) -> Response {
 /// only these (and not the rest of `~/.claude/`) preserves session
 /// history so `claude --continue` keeps working after a fresh login.
 /// Rationale + the previous wholesale-wipe shape we replaced live in
-/// [`docs/web-ui.md::Per-agent endpoints`](../../../docs/web-ui.md)
+/// [`docs/web-ui/agent.md::Per-agent endpoints`](../../../docs/web-ui/agent.md)
 /// (the `/api/logout` bullet).
 const CRED_FILE_NAMES: &[&str] = &[".credentials.json", "mcp-needs-auth-cache.json"];
 
@@ -959,7 +959,7 @@ const CRED_FILE_NAMES: &[&str] = &[".credentials.json", "mcp-needs-auth-cache.js
 /// turn loop's next iteration parks into `wait_for_login` which
 /// resumes when a fresh credentials file appears via `/login/code`.
 /// Always returns 200 with a body describing what happened. See
-/// [`docs/web-ui.md::Per-agent endpoints`](../../../docs/web-ui.md)
+/// [`docs/web-ui/agent.md::Per-agent endpoints`](../../../docs/web-ui/agent.md)
 /// (the `/api/logout` bullet) for the three-step rationale +
 /// preservation invariants.
 async fn post_logout(State(state): State<AppState>) -> Response {