feat(ecosystem): compliant Praxis/Hexis integration + vendored build

Bring the Nexus/Praxis/Hexis integration in line with
MAVEN_ECOSYSTEM_ARCHITECTURE.md:

- Praxis over HTTP: drop the in-process praxis.db open (praxisstore/
  praxistools) and call praxisd's /api/v1/tools/* API via a new praxisClient.
  Honors the "no component reads another's DB" invariant (AC#12).
  PraxisConfig.DBPath -> URL.
- Hexis confirmation gate: mutating capabilities (ReadOnly=false) now park a
  bound pendingHexis confirmation and require a spoken "да" before executing;
  read-only run immediately (AC#7, no auto attention->action).
- Capability safety: >1 verb match is ambiguous -> ask instead of firing the
  first; ambiguous Nexus resolution asks for clarification (AC#2).
- Correlation IDs on Hexis execute, recorded in the cross-service trace.
- Bug: importance arrives as JSON float64 over HTTP, not int.
- Tests: confirm-gate, decline, read-only, and ambiguity paths.

Build: vendor/ bakes in the hexis client (replace-directed at a sibling repo
outside the Docker context); Dockerfile builds from vendor and no longer
`go mod download`s the unreachable replace paths.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

vendor/github.com/coder/websocket/doc.go

@@ -0,0 +1,34 @@
+//go:build !js
+// +build !js
+
+// Package websocket implements the RFC 6455 WebSocket protocol.
+//
+// https://tools.ietf.org/html/rfc6455
+//
+// Use Dial to dial a WebSocket server.
+//
+// Use Accept to accept a WebSocket client.
+//
+// Conn represents the resulting WebSocket connection.
+//
+// The examples are the best way to understand how to correctly use the library.
+//
+// The wsjson subpackage contain helpers for JSON and protobuf messages.
+//
+// More documentation at https://github.com/coder/websocket.
+//
+// # Wasm
+//
+// The client side supports compiling to Wasm.
+// It wraps the WebSocket browser API.
+//
+// See https://developer.mozilla.org/en-US/docs/Web/API/WebSocket
+//
+// Some important caveats to be aware of:
+//
+//   - Accept always errors out
+//   - Conn.Ping is no-op
+//   - Conn.CloseNow is Close(StatusGoingAway, "")
+//   - HTTPClient, HTTPHeader and CompressionMode in DialOptions are no-op
+//   - *http.Response from Dial is &http.Response{} with a 101 status code on success
+package websocket // import "github.com/coder/websocket"