docs: update Loki queries from host to hostname label

Update all LogQL examples, agent instructions, and scripts to use
the hostname label instead of host, matching the Prometheus label
naming convention. Also update pipe-to-loki and bootstrap scripts
to push hostname instead of host.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.claude/agents/auditor.md

@@ -19,7 +19,7 @@ You may receive:
 ## Audit Log Structure
 
 Logs are shipped to Loki via promtail. Audit events use these labels:
-- `host` - hostname
+- `hostname` - hostname
 - `systemd_unit` - typically `auditd.service` for audit logs
 - `job` - typically `systemd-journal`
 
@@ -36,7 +36,7 @@ Audit log entries contain structured data:
 
 Find SSH logins and session activity:
 ```logql
-{host="<hostname>", systemd_unit="sshd.service"}
+{hostname="<hostname>", systemd_unit="sshd.service"}
 ```
 
 Look for:
@@ -48,7 +48,7 @@ Look for:
 
 Query executed commands (filter out noise):
 ```logql
-{host="<hostname>"} |= "EXECVE" != "PATH item" != "PROCTITLE" != "SYSCALL" != "BPF"
+{hostname="<hostname>"} |= "EXECVE" != "PATH item" != "PROCTITLE" != "SYSCALL" != "BPF"
 ```
 
 Further filtering:
@@ -60,28 +60,28 @@ Further filtering:
 
 Check for privilege escalation:
 ```logql
-{host="<hostname>"} |= "sudo" |= "COMMAND"
+{hostname="<hostname>"} |= "sudo" |= "COMMAND"
 ```
 
 Or via audit:
 ```logql
-{host="<hostname>"} |= "USER_CMD"
+{hostname="<hostname>"} |= "USER_CMD"
 ```
 
 ### 4. Service Manipulation
 
 Check if services were manually stopped/started:
 ```logql
-{host="<hostname>"} |= "EXECVE" |= "systemctl"
+{hostname="<hostname>"} |= "EXECVE" |= "systemctl"
 ```
 
 ### 5. File Operations
 
 Look for file modifications (if auditd rules are configured):
 ```logql
-{host="<hostname>"} |= "EXECVE" |= "vim"
-{host="<hostname>"} |= "EXECVE" |= "nano"
-{host="<hostname>"} |= "EXECVE" |= "rm"
+{hostname="<hostname>"} |= "EXECVE" |= "vim"
+{hostname="<hostname>"} |= "EXECVE" |= "nano"
+{hostname="<hostname>"} |= "EXECVE" |= "rm"
 ```
 
 ## Query Guidelines
@@ -99,7 +99,7 @@ Look for file modifications (if auditd rules are configured):
 **Time-bounded queries:**
 When investigating around a specific event:
 ```logql
-{host="<hostname>"} |= "EXECVE" != "systemd"
+{hostname="<hostname>"} |= "EXECVE" != "systemd"
 ```
 With `start: "2026-02-08T14:30:00Z"` and `end: "2026-02-08T14:35:00Z"`