BoltClam 1.0.0: ClamAV desktop protection with Bolt sign-in

Adds the PyQt6 Windows client (Homepage, Scan & results, About & updates, Settings), ClamAV scanning and quarantine, browser-download watch with an exclusive scan gate, Bolt loopback/PKCE sign-in with DPAPI key storage, Gitea release feed with checksum verification, opt-in diagnostics, and Windows/portable build tooling.

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

docs/SECURITY.md

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+# BoltClam security model
+
+BoltClam is a **signature-based second opinion**, not a replacement for
+Windows Defender or a kernel-level endpoint protection platform. This file
+states exactly what the user-mode protections do, where they stop, and what
+the app stores.
+
+## Trust boundaries
+
+- **Bolt API** (`api.themajesticnetwork.com`) is the only network service
+  BoltClam talks to. It proxies Gitea release metadata and assets, so a
+  Gitea token is never shipped to a desktop.
+- **ClamAV** is a separate, user-installed executable (`clamscan.exe` /
+  `freshclam.exe`). BoltClam runs it as the current user and parses its
+  output. BoltClam does not load ClamAV DLLs into its own process.
+- **Windows** is trusted for DPAPI, file handles, and security-center facts
+  reported by PowerShell. If PowerShell or Defender cmdlets are unavailable,
+  the UI says "not reported" rather than inventing a pass.
+- **Gitea** is trusted for release metadata only. Downloads are either
+  proxied through the Bolt API or checked against a release SHA-256 when a
+  checksum asset exists.
+
+## Credentials
+
+- Sign-in uses the existing desk API browser/PKCE flow. The password is
+  entered on a Bolt-hosted page and is never sent to BoltClam.
+- The resulting `bolt_live_...` API key is stored in
+  `%APPDATA%\BoltClam\credentials.dat` encrypted with Windows DPAPI
+  (current-user scope, with an app-specific entropy value).
+- On non-Windows development hosts the credential store falls back to a
+  mode-0600 local file and logs a warning. That fallback is for development
+  only.
+- A key is never written to `settings.json`, logs, or diagnostics bundles.
+- Sign-out revokes only the key this PC used, then deletes the local copy.
+
+## Scan and remediation
+
+- Scans run `clamscan` with `--infected --verbose --stdout` and explicit
+  argument lists (no shell). Extra options come from the user's settings and
+  are parsed; `--remove`, `--move`, and `--copy` are refused so every action
+  goes through BoltClam's recorded quarantine/delete path.
+- A detection is written to SQLite **before** remediation is attempted. If
+  quarantine or delete fails, the record stays visible as `failed` instead of
+  disappearing.
+- Quarantine moves the original file into
+  `%LOCALAPPDATA%\BoltClam\quarantine`, renames it to `.quarantine`, records
+  its SHA-256 and original path, and writes a JSON sidecar. Restore refuses to
+  overwrite an existing file. Delete is permanent and explicitly confirmed.
+- The quarantine folder is user-writable. A malicious process already running
+  as that user could tamper with it; strong tamper resistance would require a
+  privileged service and kernel driver, which this app does not install.
+
+## Real-time download gate
+
+BoltClam watches browser download folders and waits for a file's size and
+mtime to stop changing. It then:
+
+1. opens the file with `CreateFileW` and `dwShareMode = 0` (deny other
+   opens) where possible;
+2. copies it to a private temp path through that handle;
+3. scans the copy with ClamAV while the original remains locked;
+4. on a clean result, releases the lock;
+5. on a detection, closes the lock and moves the file to quarantine (or
+   deletes it if that setting was chosen).
+
+This blocks ordinary `CreateFile` opens during the scan, including a
+double-click, which is the meaningful user-mode speed bump. It is **not**:
+
+- a kernel minifilter, so a driver or a process using backup semantics can
+  bypass it;
+- a guarantee when another process already holds the file open — BoltClam
+  reports "File was in use; scanned a copy" and still remediates afterward;
+- protection for downloads made outside a watched browser download folder
+  (curl, scripts, existing files, network shares);
+- a replacement for Windows Defender's real-time engine.
+
+The **Notify only** response leaves the detected file in place. Use
+Quarantine (the default) if the machine must not retain detected downloads.
+Files larger than `BOLTCLAM_REALTIME_MAX_MB` (default 1024 MiB) are reported
+and not scanned in real time.
+
+## Definitions and updates
+
+- `freshclam` writes to BoltClam's own `%LOCALAPPDATA%\BoltClam\clamav-db`,
+  avoiding a Program Files write. `clamscan` uses that database when present
+  and otherwise falls back to the database beside the installed binary.
+- The signed-in user can see definition age in the Homepage and Settings.
+  "Fresh" means no older than seven days; older than 30 days is critical.
+- Update downloads require a valid Bolt key. If the release includes
+  `SHA256SUMS.txt`, the SHA-256 is verified before the installer is offered.
+  Without a checksum asset the UI says so rather than claiming verification.
+- Run installers only from the BoltClam Gitea releases page. The app itself
+  does not silently replace its own executable.
+
+## Diagnostics
+
+Uploading diagnostics is **opt-in and explicit**. The bundle contains:
+
+- redacted app logs;
+- settings (API key absent);
+- scan/quarantine summaries and real-time event metadata (paths redacted to
+  `%USERPROFILE%`);
+- ClamAV and system summary;
+- account email, so support can identify the upload.
+
+It never contains file contents, browser history, passwords, API keys, or
+the DPAPI credential file. Logs cap size and rotate locally.
+
+## Reporting a problem
+
+For a security issue in BoltClam or the BoltClam API, contact The Majestic
+Network directly rather than opening a public issue with exploit details.
+Include the app version, Windows version, and the relevant redacted log
+excerpt.