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/stringer.go

@@ -0,0 +1,91 @@
+// Code generated by "stringer -type=opcode,MessageType,StatusCode -output=stringer.go"; DO NOT EDIT.
+
+package websocket
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[opContinuation-0]
+	_ = x[opText-1]
+	_ = x[opBinary-2]
+	_ = x[opClose-8]
+	_ = x[opPing-9]
+	_ = x[opPong-10]
+}
+
+const (
+	_opcode_name_0 = "opContinuationopTextopBinary"
+	_opcode_name_1 = "opCloseopPingopPong"
+)
+
+var (
+	_opcode_index_0 = [...]uint8{0, 14, 20, 28}
+	_opcode_index_1 = [...]uint8{0, 7, 13, 19}
+)
+
+func (i opcode) String() string {
+	switch {
+	case 0 <= i && i <= 2:
+		return _opcode_name_0[_opcode_index_0[i]:_opcode_index_0[i+1]]
+	case 8 <= i && i <= 10:
+		i -= 8
+		return _opcode_name_1[_opcode_index_1[i]:_opcode_index_1[i+1]]
+	default:
+		return "opcode(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+}
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[MessageText-1]
+	_ = x[MessageBinary-2]
+}
+
+const _MessageType_name = "MessageTextMessageBinary"
+
+var _MessageType_index = [...]uint8{0, 11, 24}
+
+func (i MessageType) String() string {
+	i -= 1
+	if i < 0 || i >= MessageType(len(_MessageType_index)-1) {
+		return "MessageType(" + strconv.FormatInt(int64(i+1), 10) + ")"
+	}
+	return _MessageType_name[_MessageType_index[i]:_MessageType_index[i+1]]
+}
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[StatusNormalClosure-1000]
+	_ = x[StatusGoingAway-1001]
+	_ = x[StatusProtocolError-1002]
+	_ = x[StatusUnsupportedData-1003]
+	_ = x[statusReserved-1004]
+	_ = x[StatusNoStatusRcvd-1005]
+	_ = x[StatusAbnormalClosure-1006]
+	_ = x[StatusInvalidFramePayloadData-1007]
+	_ = x[StatusPolicyViolation-1008]
+	_ = x[StatusMessageTooBig-1009]
+	_ = x[StatusMandatoryExtension-1010]
+	_ = x[StatusInternalError-1011]
+	_ = x[StatusServiceRestart-1012]
+	_ = x[StatusTryAgainLater-1013]
+	_ = x[StatusBadGateway-1014]
+	_ = x[StatusTLSHandshake-1015]
+}
+
+const _StatusCode_name = "StatusNormalClosureStatusGoingAwayStatusProtocolErrorStatusUnsupportedDatastatusReservedStatusNoStatusRcvdStatusAbnormalClosureStatusInvalidFramePayloadDataStatusPolicyViolationStatusMessageTooBigStatusMandatoryExtensionStatusInternalErrorStatusServiceRestartStatusTryAgainLaterStatusBadGatewayStatusTLSHandshake"
+
+var _StatusCode_index = [...]uint16{0, 19, 34, 53, 74, 88, 106, 127, 156, 177, 196, 220, 239, 259, 278, 294, 312}
+
+func (i StatusCode) String() string {
+	i -= 1000
+	if i < 0 || i >= StatusCode(len(_StatusCode_index)-1) {
+		return "StatusCode(" + strconv.FormatInt(int64(i+1000), 10) + ")"
+	}
+	return _StatusCode_name[_StatusCode_index[i]:_StatusCode_index[i+1]]
+}