docs: fix README inaccuracies found during QA audit (#74)

## Summary

Fixes documentation inaccuracies in README.md identified during QA audit.

### Changes

**API table (closes #67):**
- Removed `GET /api/v1/domains` and `GET /api/v1/hostnames` from the HTTP API table. These endpoints are not implemented — the only routes in `internal/server/routes.go` are `/health`, `/api/v1/status`, and `/metrics` (conditional).

**Feature claims (closes #68):**
- Removed "Inconsistency resolved" from hostname monitoring features. `detectInconsistencies()` detects current inconsistencies but has no state tracking to detect when they resolve.
- Removed `nxdomain` and `nodata` from the state status values table. While the resolver defines these constants, `buildHostnameState()` in the watcher only ever sets status to `"ok"`. Failed queries set `"error"` via the NS disappearance path. These values are never written to state.
- Removed "Empty response" (NODATA/NXDOMAIN) detection claim. Changes are caught generically by `detectRecordChanges()`, not with specific NODATA/NXDOMAIN labeling.

### What was NOT changed

- "Inconsistency detected" remains — this IS implemented in `detectInconsistencies()`.
- All other feature claims were verified against the code and are accurate.
- No Go source code was modified.

Co-authored-by: clawbot <clawbot@noreply.git.eeqj.de>
Co-authored-by: Jeffrey Paul <sneak@noreply.example.org>
Reviewed-on: #74
Co-authored-by: clawbot <clawbot@noreply.example.org>
Co-committed-by: clawbot <clawbot@noreply.example.org>

README.md

@@ -52,10 +52,6 @@ without requiring an external database.
     responding again.
   - **Inconsistency detected**: Two nameservers that previously agreed
     now return different record sets for the same hostname.
-  - **Inconsistency resolved**: Nameservers that previously disagreed
-    are now back in agreement.
-  - **Empty response**: A nameserver that previously returned records
-    now returns an authoritative empty response (NODATA/NXDOMAIN).
 
 ### TCP Port Monitoring
 
@@ -136,8 +132,6 @@ dnswatcher exposes a lightweight HTTP API for operational visibility:
 |---------------------------------------|--------------------------------|
 | `GET /health`                         | Health check (JSON)            |
 | `GET /api/v1/status`                  | Current monitoring state       |
-| `GET /api/v1/domains`                 | Configured domains and status  |
-| `GET /api/v1/hostnames`              | Configured hostnames and status|
 | `GET /metrics`                        | Prometheus metrics (optional)  |
 
 ---
@@ -325,8 +319,6 @@ tracks reachability:
 |-------------|-------------------------------------------------|
 | `ok`        | Query succeeded, records are current             |
 | `error`     | Query failed (timeout, SERVFAIL, network error)  |
-| `nxdomain`  | Authoritative NXDOMAIN response                  |
-| `nodata`    | Authoritative empty response (NODATA)            |
 
 ---