feat: hardware compatibility, TPM attestation, security audit prep

- Y2-01: docs/hardware-compatibility.md — 2 certified platforms,
  4 planned, minimum requirements, known quirks
- Y3-04: tpm.rs — TPM 2.0 attestation types (TpmStatus, TpmAttestation,
  detect_tpm), ready for tss-esapi integration
- Y5-03: docs/security-audit-prep.md — audit scope, completed internal
  audits, recommended firms, budget estimates

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

core/archipelago/src/main.rs

@@ -38,7 +38,7 @@ mod names;
 mod network;
 mod nostr_relays;
 mod update;
-mod vpn;
+mod tpm;mod vpn;
 mod webhooks;
 
 use auth::AuthManager;

core/archipelago/src/tpm.rs

@@ -0,0 +1,52 @@
+//! TPM 2.0 hardware attestation module.
+//!
+//! Nodes with TPM chips can cryptographically prove their hardware identity,
+//! adding a trust layer to federation. The TPM attestation key is included
+//! in the node's DID Document as an additional verification method.
+//!
+//! Requires: tss-esapi crate (TPM2 Software Stack) and physical TPM 2.0 chip.
+
+use serde::{Deserialize, Serialize};
+
+/// TPM attestation status for a node.
+#[derive(Debug, Clone, Default, Serialize, Deserialize)]
+pub struct TpmStatus {
+    /// Whether a TPM 2.0 chip was detected
+    pub available: bool,
+    /// TPM manufacturer info
+    pub manufacturer: Option<String>,
+    /// Firmware version
+    pub firmware_version: Option<String>,
+    /// Whether an attestation key has been generated
+    pub attestation_key_created: bool,
+    /// Public part of the attestation key (hex)
+    pub attestation_pubkey: Option<String>,
+}
+
+/// TPM attestation for inclusion in DID Documents.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct TpmAttestation {
+    /// Attestation type (e.g., "TpmAttestationKey2023")
+    pub attestation_type: String,
+    /// TPM public key (hex-encoded)
+    pub public_key: String,
+    /// Platform Certificate (if available)
+    pub platform_cert: Option<String>,
+    /// Quote signature over node's DID (proves TPM controls this identity)
+    pub quote_signature: Option<String>,
+}
+
+/// Check if TPM 2.0 is available on this system.
+pub fn detect_tpm() -> TpmStatus {
+    // Check /dev/tpm0 or /dev/tpmrm0
+    let tpm_device = std::path::Path::new("/dev/tpmrm0").exists()
+        || std::path::Path::new("/dev/tpm0").exists();
+
+    TpmStatus {
+        available: tpm_device,
+        manufacturer: None,
+        firmware_version: None,
+        attestation_key_created: false,
+        attestation_pubkey: None,
+    }
+}