v0.8.0: dep prune, memtest introspection fix, concurrent uploads, x-api-key

Dependency cleanup (ponytail audit):
- Drop 14 unused dependency declarations across 7 crates; quick-xml and
  x509-parser leave the tree entirely (SAML cert/XML work is handled by
  bergshamra + roxmltree).

Fixes:
- introspect: drop the over-broad "microsoft" UTF-16 bulk-scan marker that
  mislabeled Secure-Boot-signed non-Windows bootables (memtest86, signed
  BSDs, firmware tools) as Windows — the string lives in their MS-signed
  EFI loader's FAT long-filename entries. INTROSPECT_REV 3 -> 4 re-probes
  existing local ISOs on startup so the bogus label clears on upgrade.
- upload: begin_upload now reclaims an abandoned <id>.partial instead of
  rejecting the re-upload with "already uploading". Robust against browser
  refresh, tab close, and dropped connections (the chunked protocol can't
  resume a dead session anyway).

Features:
- Storage upload: multi-file + concurrent. Each dropped/selected .iso gets
  its own progress row and uploads independently; a single page-leave guard
  plus a pagehide keepalive-abort replace the old shared singletons.
- Operator API key (x-api-key): a persisted key authenticates /api/* exactly
  like an operator session, for Postman/scripts. New core ApiKeyStore
  (generated on first run, regenerable), accepted in require_auth alongside
  the session cookie, surfaced in Settings -> Advanced with copy + regenerate
  and a usage reference. GET /api/api-key + POST /api/api-key/regenerate.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

crates/iso-store/Cargo.toml

@@ -12,16 +12,13 @@ workspace = true
 [dependencies]
 openpxe-core.workspace = true
 tokio = { workspace = true }
-tokio-util = { workspace = true }
 serde.workspace = true
 serde_json.workspace = true
 tracing.workspace = true
-thiserror.workspace = true
 anyhow.workspace = true
 sha2.workspace = true
 hex.workspace = true
 bcrypt.workspace = true
-uuid.workspace = true
 time.workspace = true
 parking_lot.workspace = true
 bytes.workspace = true