crucible depot: Increment 1 core (status/push/verify/get/pull + local/cdn/bunny backends) (#30)

Implements Increment 1 of `docs/superpowers/specs/2026-07-04-crucible-depot-core-design.md`: a new stdlib-only `internal/depot` package wired into the dispatcher.

- `crucible depot status|push|verify|get|pull` with backends `local`/`cdn`/`bunny`; exit contract `0` clean / `1` drift / `2` unconfirmed-only / `64` usage / `70` internal.
- Presence is always probed against the real target (IPv4 1-byte range GET; HEAD is banned with a regression-tripwire test). `unconfirmed` is a distinct state, never collapsed into `missing`.
- No prompting anywhere: missing `BUNNY_STORAGE_*` env fails closed (read path included), enforced by a no-stdin test.
- Uploads: probe-then-PUT with `Checksum: <UPPER-sha>`; read/write key split (`BUNNY_STORAGE_READ_PASSWORD` falls back to `BUNNY_STORAGE_PASSWORD`).
- Field-driven fix included: per-probe transient retry (curl `--retry 2` equivalent) — without it a real 1490-blob CDN sweep reported 1222 false-unconfirmed; with it, 1490/1490 present in 74s, exit 0.
- Registry: depot `Wired: true`, joins the interactive menu; stale "(SeaweedFS)" wording removed.

Tests: unit + httptest fake-Bunny (probe sequence, Checksum header, key split, 428 throttling → exit 2) + local→bunny integration (drift → push → clean → idempotent no-second-PUT; incremental pull). `make check` green.

**Merge ordering:** this merges FIRST; the companion `sow-assets-manifest#crucible-depot-cutover` PR needs its flake input bumped to include this.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Reviewed-on: #30
Reviewed-by: xtul <mpiasecki720@protonmail.com>
Co-authored-by: vickydotbat <vickydotbat@tutamail.com>
Co-committed-by: vickydotbat <vickydotbat@tutamail.com>

internal/depot/config.go

@@ -0,0 +1,102 @@
+package depot
+
+import (
+	"strconv"
+	"time"
+)
+
+type Config struct {
+	CDNBase        string
+	StorageHost    string
+	StorageZone    string
+	ReadKey        string
+	WriteKey       string
+	ProbeJobs      int
+	Jobs           int
+	ConnectTimeout time.Duration
+	ProbeMaxTime   time.Duration
+	ConfirmRetries int
+	ConfirmMax     int
+}
+
+func LoadConfig(getenv func(string) string) Config {
+	cfg := Config{
+		CDNBase:        "https://cdn-a7f3k9.westgate.pw",
+		StorageZone:    "sow-assets-depot",
+		ProbeJobs:      16,
+		Jobs:           16,
+		ConnectTimeout: 10 * time.Second,
+		ProbeMaxTime:   30 * time.Second,
+		ConfirmRetries: 3,
+		ConfirmMax:     200,
+	}
+
+	// DEPOT_CDN_BASE || BUNNY_CDN_BASE
+	if v := getenv("DEPOT_CDN_BASE"); v != "" {
+		cfg.CDNBase = v
+	} else if v := getenv("BUNNY_CDN_BASE"); v != "" {
+		cfg.CDNBase = v
+	}
+
+	// BUNNY_STORAGE_HOST (no default)
+	cfg.StorageHost = getenv("BUNNY_STORAGE_HOST")
+
+	// BUNNY_STORAGE_ZONE (default "sow-assets-depot")
+	if v := getenv("BUNNY_STORAGE_ZONE"); v != "" {
+		cfg.StorageZone = v
+	}
+
+	// BUNNY_STORAGE_PASSWORD
+	cfg.WriteKey = getenv("BUNNY_STORAGE_PASSWORD")
+
+	// BUNNY_STORAGE_READ_PASSWORD || BUNNY_STORAGE_PASSWORD
+	if v := getenv("BUNNY_STORAGE_READ_PASSWORD"); v != "" {
+		cfg.ReadKey = v
+	} else {
+		cfg.ReadKey = cfg.WriteKey
+	}
+
+	// DEPOT_PROBE_JOBS (default 16)
+	if v := getenv("DEPOT_PROBE_JOBS"); v != "" {
+		if i, err := strconv.Atoi(v); err == nil {
+			cfg.ProbeJobs = i
+		}
+	}
+
+	// DEPOT_JOBS (default 16)
+	if v := getenv("DEPOT_JOBS"); v != "" {
+		if i, err := strconv.Atoi(v); err == nil {
+			cfg.Jobs = i
+		}
+	}
+
+	// DEPOT_CONNECT_TIMEOUT (default 10s)
+	if v := getenv("DEPOT_CONNECT_TIMEOUT"); v != "" {
+		if d, err := time.ParseDuration(v + "s"); err == nil {
+			cfg.ConnectTimeout = d
+		}
+	}
+
+	// DEPOT_PROBE_MAX_TIME (default 30s)
+	if v := getenv("DEPOT_PROBE_MAX_TIME"); v != "" {
+		if d, err := time.ParseDuration(v + "s"); err == nil {
+			cfg.ProbeMaxTime = d
+		}
+	}
+
+	// DEPOT_CONFIRM_RETRIES (default 3)
+	if v := getenv("DEPOT_CONFIRM_RETRIES"); v != "" {
+		if i, err := strconv.Atoi(v); err == nil {
+			cfg.ConfirmRetries = i
+		}
+	}
+
+	// DEPOT_CONFIRM_MAX (default 200, 0 = unlimited)
+	if v := getenv("DEPOT_CONFIRM_MAX"); v != "" {
+		if i, err := strconv.Atoi(v); err == nil {
+			cfg.ConfirmMax = i
+		}
+	}
+
+	return cfg
+}