docs(turn-loop): document passwordlessSudo, dashboardLinks, extraFiles, connectivity overrides

Five previously undocumented per-agent agent.nix options:

- hyperhive.user.passwordlessSudo: default-true sudo grant; note added
  with cross-reference to companion user.* options in agent-hierarchy.md
- hyperhive.dashboardLinks: declarative extra nav links on the dashboard
  card and per-agent page header; table of fields (label/url/icon)
- hyperhive.frontend.extraFiles: overlay files over the default agent dist;
  source/target semantics, constraints, collision guard, mergedDist
- hyperhive.forge.url: per-agent Forgejo base URL for tea login; default
  localhost:3000; validation note
- hyperhive.matrix.url: per-agent matrix-sdk homeserver URL; default
  localhost:8008; per-agent override use-cases (remote hive, VPN)

docs/turn-loop.md

@@ -291,6 +291,116 @@ write_settings, write_system_prompt, run_turn, drive_turn,
 emit_turn_end, wait_for_login, compact_session}` so the two binaries
 can't drift.
 
+### `user.passwordlessSudo`
+
+```nix
+hyperhive.user.passwordlessSudo = true;  # default
+```
+
+Grants the per-agent unix user passwordless `sudo` (`NOPASSWD: ALL`).
+Enabled by default so claude's shell tools work for operations that
+need root inside the container (`systemctl`, package managers in dev
+shells, etc.) — the same privilege surface the previous root-user shape
+had, now elevated explicitly rather than implicitly.
+
+Set to `false` for agents that should be strictly unprivileged.
+Any tool invocation that needs root then fails loudly with the standard
+sudo rejection rather than silently succeeding — easier to audit.
+
+`hyperhive.user.uid`, `hyperhive.user.gid`, and
+`hyperhive.user.name` are the companion options; see
+`docs/agent-hierarchy.md` — "Harness systemd unit shape" for the full
+`user.*` surface.
+
+### Dashboard links
+
+```nix
+hyperhive.dashboardLinks = [
+  { label = "Stats"; icon = "📊"; url = "http://localhost:9001/stats"; }
+  { label = "Scratchpad"; url = "http://localhost:8080"; }
+];
+```
+
+Declares extra navigation links that appear on the agent's dashboard
+card and in the per-agent page header alongside the built-in forge /
+config / container links. Each entry has:
+
+| Field | Required | Description |
+|-------|----------|-------------|
+| `label` | yes | Display text shown in the icon strip tooltip and meta-nav. |
+| `url` | yes | Absolute URL — may include a different port (the dashboard renders it as a plain anchor). |
+| `icon` | no | Emoji or short glyph prefix. Defaults to empty string. |
+
+The list is written to `<state>/hyperhive-dashboard-links.json` by a
+one-shot systemd unit at container boot. `hive-c0re` reads the file on
+each container-view snapshot and attaches the links to the agent card
+(`kind = External`) without any code change. Omitting the option
+(default empty) produces no extra links.
+
+### Custom static files
+
+```nix
+hyperhive.frontend.extraFiles = {
+  "games/bitburner" = {
+    source = ./bitburner-dist;   # path relative to agent.nix
+    # target defaults to attribute name: "games/bitburner"
+  };
+  "my-page" = {
+    source = ./my-page.html;
+    target = "my-page.html";    # explicit override
+  };
+};
+```
+
+Layers additional files over the default per-agent web UI dist. Each
+attribute defines one overlay entry:
+
+- **`source`** — a Nix path (file or directory) copied into the merged
+  static tree. Evaluated at nix build time; the resulting derivation is
+  pointed at by `HIVE_STATIC_DIR`.
+- **`target`** — destination path within the merged tree, used as both
+  the served URL prefix (`/<target>/…`) and the on-disk layout.
+  Defaults to the attribute name. Forward slashes create nested layouts
+  (`"games/bitburner"` serves at `/games/bitburner/…`).
+
+Constraints: `target` must start with an alphanumeric or `_` and
+contain only alphanumerics, `_`, `.`, `/`, `-`. `..` segments are
+rejected by a config assertion. The merge step refuses to overwrite
+files already present in the default dist — pick a target name that
+does not collide with existing paths (`static/`, `index.html`, etc.).
+
+The default dist ships at `hyperhive.frontend.dist` (the
+`hyperhive-frontend` package output, read-only). To replace the
+entire UI rather than layer on top, override `frontend.dist` directly.
+
+### Connectivity overrides
+
+Two `hyperhive.forge.*` / `hyperhive.matrix.*` options override where
+the per-agent daemons connect. Both rarely need changing on a standard
+single-host deploy, but are useful for multi-hive or custom-network
+setups.
+
+```nix
+hyperhive.forge.url = "http://localhost:3000";   # default
+hyperhive.matrix.url = "http://localhost:8008";  # default
+```
+
+**`hyperhive.forge.url`** — base URL of the Forgejo instance. Used by
+a one-shot boot unit that runs `tea login add --url <url> --token
+$(cat $HYPERHIVE_STATE_DIR/forge-token)`, making `tea` and
+`hive-forge` work without an extra auth step. The unit is a no-op
+when `forge-token` is absent. Override when the agent should connect
+to a Forgejo on a different host or port (e.g. a swarm peer's forge).
+Validated: must be an `http://` or `https://` URL or the empty string.
+
+**`hyperhive.matrix.url`** — homeserver URL used by
+`hive-matrix-daemon` when connecting via the matrix-sdk. Default
+points at the in-host tuwunel (`localhost:8008`), reachable over the
+host loopback in shared-netns mode. Override per-agent when an agent
+should talk to a different homeserver — for example a remote hive's
+tuwunel reached over a VPN, or an external Matrix server for a
+federation-only agent.
+
 ## MCP surface
 
 The harness ships an embedded MCP server (rmcp 1.7). Claude launches