feat(inventory): deep hardware capture + per-probe substeps + verbose logs

Extend Inventory stage from a one-liner summary to a per-probe substep
emitter with ~20-30 narrative log lines per run.

- spec: per-DIMM memory (slot/size/speed/manufacturer/part_number),
  richer CPU (vendor/stepping/physical_cores/flags), disk
  model/transport/rotational, NIC driver/pci_addr, GPU vram/pci/driver,
  new System/Baseboard/PSU/OS top-level sections. All fields omitempty
  so existing expected-spec YAML and artifacts stay compatible.
- spec.Diff: new diffDIMMs/diffSystem/diffBaseboard/diffPSU/diffOS
  helpers; extended diffDisks/diffNICs/diffGPUs for new fields. GPU
  diff gains PCIAddr-pinned matching alongside count-by-model.
- agent/probes/inventory: CPU (/proc/cpuinfo extended), Memory
  (dmidecode -t 17 multi-block), Disks (+model/transport/rotational),
  NICs (+driver/pci from sysfs), GPUs (VRAM from lspci -vv),
  new System/Baseboard (dmidecode -t system/baseboard), PSU
  (dmidecode -t 39), OS (/proc/sys/kernel/osrelease + /etc/os-release).
  All probes accept a Logger and emit per-finding info/warn lines.
- agent/probes/firmware: parseDmidecodeAllSections for multi-block
  fixtures (memory / PSU).
- agent/runner: Inventory case becomes 9 substep rows (CPU / Memory /
  Disks / NICs / GPUs / System / Baseboard / PSU / OS) with per-probe
  start/complete timestamps.
- report: new Inventory HTML section between Stages and Firmware;
  resolveReporting loads the inventory.json artifact.
- agent/tests/fakes/dmidecode: dispatches on -t flag to serve bios /
  memory / system / baseboard / 39 fixtures for unit tests.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

agent/probes/firmware_test.go

@@ -230,3 +230,45 @@ func TestIsRealNIC(t *testing.T) {
 		}
 	}
 }
+
+// dmidecode -t 39 fixture with two PSU blocks. Verifies that
+// parseDmidecodeAllSections returns every matching block, not just the
+// first (which was the old parseDmidecodeSection behavior).
+const dmidecodePSU = `# dmidecode 3.3
+
+Handle 0x0040, DMI type 39, 22 bytes
+System Power Supply
+	Location: PSU1
+	Manufacturer: DELTA
+	Model Part Number: ABC760
+	Max Power Capacity: 760 W
+	Status: Present, OK
+
+Handle 0x0041, DMI type 39, 22 bytes
+System Power Supply
+	Location: PSU2
+	Manufacturer: DELTA
+	Model Part Number: ABC760
+	Max Power Capacity: 760 W
+	Status: Present, Unplugged
+`
+
+func TestParseDmidecodeAllSections(t *testing.T) {
+	blocks := parseDmidecodeAllSections(strings.NewReader(dmidecodePSU), "System Power Supply")
+	if len(blocks) != 2 {
+		t.Fatalf("expected 2 blocks, got %d", len(blocks))
+	}
+	if blocks[0]["Location"] != "PSU1" || blocks[1]["Location"] != "PSU2" {
+		t.Fatalf("locations wrong: %+v", blocks)
+	}
+	if blocks[1]["Status"] != "Present, Unplugged" {
+		t.Fatalf("psu2 status: %q", blocks[1]["Status"])
+	}
+}
+
+func TestParseDmidecodeAllSectionsEmpty(t *testing.T) {
+	blocks := parseDmidecodeAllSections(strings.NewReader(""), "Memory Device")
+	if len(blocks) != 0 {
+		t.Fatalf("expected 0 blocks on empty input, got %d", len(blocks))
+	}
+}