Per-device tokens with revocation (issue #11)

Auth previously used the shared IRIS_TOKEN as the security principal:
a leaked token meant access to all devices, and a compromised device
could not be isolated.

Gateway:
- pairing.py: devices.token column (in-place migration) + revoked
  denylist table; issue_token (idempotent, 64 hex), token_for,
  reissue_token, revoke/unrevoke/is_revoked/list_revoked. The token
  never leaks into device dicts (push fan-out / listings).
- http_server.py: auth accepts the shared token (bootstrap/legacy) OR
  the device's own token (both constant-time); a revoked device_id is
  rejected with 401 before either comparison. On SSE open (pairing)
  the per-device token is minted and returned in hello.ack.
- protocol.py: hello_ack(..., device_token).
- adapter.py: setup flow (hermes gateway setup -> Iris) now offers
  'Remove a paired device?' on an existing setup: numbered select
  menu (last option = exit the removal loop), confirmation, back to
  the menu for further removals.
- tools/iris_devices.py: operator CLI (list / revoke / unrevoke /
  reissue), stdlib only.

App:
- SecureStore.deviceToken (Android: EncryptedSharedPreferences;
  Desktop: second keyring slot iris-device-token / device_token.enc).
- HelloAckPayload.deviceToken; GatewayClient stores it on hello and
  presents it instead of the shared token from then on (live provider
  in HttpGateway); savePairing/clear wipe it for re-pairing.

Docs: 09 §9.3 stretch -> implemented (revocation semantics, both
control surfaces), 04 hello.ack example, frames.schema.json, M7 row 13.

Tests: 8 new Python tests (issuance, acceptance, revocation,
isolation, unrevoke, registry unit x2, setup-flow menu) - 94/94 pass;
2 new Kotlin wire tests - green. Live-verified against a running
gateway (hello.ack token matches devices.db; revoke -> 401 even with
shared token; unrevoke -> 200; setup TUI both paths).

README.md

@@ -60,7 +60,7 @@ Setup: [`docs/setup.md`](docs/setup.md) §4; details:
 ### Prerequisites
 
 | Where | You need |
-|---|---|
+| --- | --- |
 | Gateway host | [hermes-agent](https://github.com/NousResearch/hermes-agent) with its venv (`uv sync`) |
 | Android build machine | JDK 17, Android SDK (`sdk.dir` in `app/local.properties` or `ANDROID_HOME`), ADB with a connected device |
 | Desktop build machine | JDK 17 only |
@@ -129,7 +129,7 @@ Contributions are welcome! Before you start:
 2. **Know the layout.**
 
    | Path | What |
-   |---|---|
+   | --- | --- |
    | `gateway-plugin/` | Python hermes platform plugin (`android`); `protocol.py` is the frame source of truth |
    | `app/shared` | KMP module with most of the client code (shared by Android + Desktop) |
    | `app/androidApp` | Thin Android shell (package `dev.iris.app`) |
@@ -152,4 +152,4 @@ Open an issue first for anything big, then send a pull request.
 
 ## License
 
-Apache License 2.0 — see [LICENSE](LICENSE).
+Apache License 2.0 — see [LICENSE](LICENSE).