chore(agent): add CHANGELOG, version the agent at 0.1.0

- CHANGELOG.md with the v0.1.0 (slice 1) entry
- main: version var (0.1.0, ldflags-overridable) + --version flag; version shown
  in selftest header and startup log

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -0,0 +1,55 @@
+# Changelog
+
+All notable changes to **felhom-agent** are recorded here. Update on every code
+change that gets pushed.
+
+## v0.1.0 — Scaffold + `proxmox` interaction layer (slice 1) (2026-06-08)
+
+First slice: stand up the host-agent project and its foundation — the typed
+Proxmox interaction layer every other module will call. No reconcile loop, hub
+client, signing, or storage/backup orchestration yet (later slices).
+
+### Added
+- **Project scaffold**: module `gitea.dooplex.hu/admin/felhom-agent`, binary
+  `felhom-agent` (`cmd/felhom-agent/`), Go 1.24, zero external dependencies
+  (pure stdlib). `--version` flag; `version` var overridable via
+  `-ldflags "-X main.version=<v>"`.
+- **`internal/proxmox` — API backend (`Client`)**: hand-rolled REST client over
+  `https://<host>:8006/api2/json` with `PVEAPIToken` auth. Typed read ops
+  (`Version`, `Nodes`, `NodeStatus`, `ListLXC`, `GuestStatus`, `GuestConfig`,
+  `ListStorage`, `NodeStorage`, `StorageContent`) and async mutating ops
+  returning a UPID (`RestoreLXC` — the primary create path, `Vzdump`, `Snapshot`,
+  `Rollback`, `DeleteSnapshot`, `SetConfig`, `Start`, `Stop`).
+- **`WaitTask`**: polls `GET /nodes/{node}/tasks/{upid}/status` until stopped, then
+  asserts `exitstatus == "OK"` (authorization can surface at task execution, not
+  the POST — phase1-2 §1.3). Exponential backoff (1s→5s cap), context
+  cancellation + timeout. `*APIError` parses the offending privilege from a 403;
+  `*TaskError` parses it from a failed task exitstatus + log tail.
+- **`internal/proxmox` — fenced root-CLI backend (`Privileged`)**: limited to the
+  three proven OS-root exceptions only — `CreateGoldenLXC` (keyctl `pct create`),
+  `MountUSBByUUID`, `SMART`, `Sensors`; each cites why it can't be the API. Fence
+  is structural (Client never shells out, Privileged never makes an HTTP call) and
+  asserted in tests.
+- **TLS trust**: SHA-256 leaf-cert pinning (the host serves a self-signed cert) or
+  a CA file; an explicitly-named `insecure_skip_verify` that is off by default. No
+  blanket verification disable.
+- **`internal/config`**: JSON config file + `FELHOM_AGENT_*` env overrides; the
+  token secret is never logged (`Redacted()`).
+- **`internal/log`**: slog setup (text, stderr, configurable level).
+- **`cmd/felhom-agent --selftest`**: read-only health report against a live host
+  (version/nodes/status/guests/storage); `--selftest=task --vmid N` exercises
+  `WaitTask` on a reversible snapshot→rollback→delete op (gated; default selftest
+  mutates nothing).
+- **Tests**: unit tests with a mock HTTP transport + mock runner (UPID parse,
+  `WaitTask` running→OK / failed-403 / timeout / ctx-cancel, 403→privilege error,
+  response decoding against shapes captured live from `demo-felhom`, config
+  redaction, and the API-vs-root routing fence).
+
+### Notes
+- Types are grounded in the spike findings
+  (`felhom.eu/documentation/proxmox-platform.md`, `tests/phase{0,1-2,3}-findings.md`)
+  and the exact JSON shapes captured live from `demo-felhom` (PVE 9.2.2).
+- Verified: `go build/vet/test` green on Go 1.24.4 (build server) and a live
+  read-only `--selftest` against the demo host with TLS fingerprint pinning.
+- The 16-privilege `FelhomAgent` role + privsep token (role on **both** user and
+  token) is provisioned out-of-band; the agent only consumes the token.

cmd/felhom-agent/main.go

@@ -22,17 +22,28 @@ import (
 	"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
 )
 
+// version is the agent version. Overridable at build time with
+// -ldflags "-X main.version=<v>"; defaults to the in-repo CHANGELOG version.
+var version = "0.1.0"
+
 func main() {
 	var (
-		cfgPath  string
-		selftest selftestFlag
-		vmid     int
+		cfgPath     string
+		selftest    selftestFlag
+		vmid        int
+		showVersion bool
 	)
 	flag.StringVar(&cfgPath, "config", envOr("FELHOM_AGENT_CONFIG", "/etc/felhom-agent/agent.json"), "path to the agent config file (JSON)")
 	flag.Var(&selftest, "selftest", "run a self-test and exit: bare/`read` = read-only queries; `task` = reversible mutating exercise (needs -vmid)")
 	flag.IntVar(&vmid, "vmid", 0, "guest VMID for --selftest=task (the reversible snapshot/rollback exercise)")
+	flag.BoolVar(&showVersion, "version", false, "print version and exit")
 	flag.Parse()
 
+	if showVersion {
+		fmt.Println("felhom-agent", version)
+		return
+	}
+
 	cfg, err := config.Load(cfgPath)
 	if err != nil {
 		// A missing default config file is fine if env provides the values; only a
@@ -48,7 +59,8 @@ func main() {
 	switch selftest.mode {
 	case "":
 		// No daemon loop yet.
-		logger.Info("felhom-agent slice-1 scaffold; no run loop yet",
+		logger.Info("felhom-agent scaffold; no run loop yet",
+			"version", version,
 			"hint", "use --selftest (read-only) or --selftest=task --vmid N")
 		// TODO: poll loop — slice 3/4.
 		return
@@ -87,7 +99,7 @@ func runSelftestRead(ctx context.Context, cfg config.Config, logger *slog.Logger
 	ctx, cancel := context.WithTimeout(ctx, 30*time.Second)
 	defer cancel()
 
-	fmt.Println("=== felhom-agent selftest (read-only) ===")
+	fmt.Printf("=== felhom-agent %s selftest (read-only) ===\n", version)
 	fmt.Printf("endpoint : %s  node=%s\n", cfg.Proxmox.Endpoint, cfg.Proxmox.Node)
 
 	fail := 0