feat: Agent distribution with secure enrollment from the control panel

One universal Windows Agent package per version (agent_releases: version/
platform/architecture/sha256/status DRAFT|PUBLISHED|REVOKED; the binary
lives on a local release-storage volume, never in PostgreSQL). An operator
creates a pending installation (agent_enrollments) from Agents / Servidores
-> + Nova instalação, then either downloads it directly or generates a
one-time HTTPS link (short TTL, single use). Either path streams the
package plus a freshly minted enrollment.json whose token is never written
to storage in plaintext, only its SHA-256 hash. On the client host,
gti-agent.ps1 install-auto verifies the bundle's SHA-256, refuses a non-
HTTPS Hub, enrolls via POST /v1/agents/enroll (deleting the enrollment
token immediately after, success or failure), writes an ACL-restricted
.env with the newly issued permanent Agent token, and registers the
Windows Service without starting it (Firebird stays unconfigured on
purpose). Idempotent, replay-proof, rate-limited per IP, fully audited,
never logs a secret.

Migration 0022_agent_releases_enrollment (verified fresh-DB ==
upgrade-from-0021 by pg_dump diff). GTI_FISCAL_VERSION/AGENT_VERSION
bumped to 1.1.0 as the single source of truth across code, packages, the
release manifest and every published AgentRelease row.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

central/app/enrollment.py

@@ -0,0 +1,84 @@
+"""Secrets and package bundling for Agent distribution.
+
+Two independent secrets guard the distribution flow, both random(256 bits),
+single-use and short-TTL, both stored only as SHA-256 hashes:
+
+- the *download* token: embedded in the shareable link an operator hands to
+  whoever installs the Agent (or clicked directly, authenticated, from the
+  panel);
+- the *enrollment* token: embedded inside the downloaded bundle as
+  `enrollment.json`, consumed exactly once by `POST /v1/agents/enroll`.
+
+Neither token is ever the Agent's own permanent Bearer token (issued only
+after a successful enrollment) and neither is ever logged or audited in
+plaintext.
+"""
+from __future__ import annotations
+
+import hashlib
+import hmac
+import io
+import json
+import re
+import secrets
+import zipfile
+from dataclasses import dataclass
+
+
+class EnrollmentRejected(Exception):
+    def __init__(self, reason: str):
+        super().__init__(reason)
+        self.reason = reason
+
+
+def new_token() -> str:
+    """256 bits of randomness, URL-safe — usable directly in a link or a JSON field."""
+    return secrets.token_urlsafe(32)
+
+
+def token_digest(token: str) -> str:
+    return hashlib.sha256(token.encode()).hexdigest()
+
+
+def token_matches(token: str | None, stored_hash: str | None) -> bool:
+    if not token or not stored_hash:
+        return False
+    return hmac.compare_digest(token_digest(token), stored_hash)
+
+
+ENROLLMENT_UUID_RE = re.compile(r"^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$")
+
+
+def valid_uuid(value: str | None) -> bool:
+    return bool(value) and bool(ENROLLMENT_UUID_RE.match(value))
+
+
+@dataclass(frozen=True)
+class BundlePlan:
+    hub_url: str
+    enrollment_uuid: str
+    enrollment_token: str
+    enroll_path: str = "/v1/agents/enroll"
+
+
+def build_bundle(release_zip_bytes: bytes, plan: BundlePlan) -> bytes:
+    """Return a new zip = the release zip's entries plus one
+    `<package-root>/enrollment.json` holding only temporary, single-use data.
+    Never a permanent credential — that is issued only once enrollment succeeds."""
+    with zipfile.ZipFile(io.BytesIO(release_zip_bytes)) as source:
+        names = source.namelist()
+        if not names:
+            raise EnrollmentRejected("EMPTY_RELEASE_PACKAGE")
+        root = names[0].split("/", 1)[0]
+        out = io.BytesIO()
+        with zipfile.ZipFile(out, "w", zipfile.ZIP_DEFLATED) as dest:
+            for name in names:
+                dest.writestr(name, source.read(name))
+            payload = {
+                "installation_id": plan.enrollment_uuid,
+                "enrollment_token": plan.enrollment_token,
+                "hub_url": plan.hub_url,
+                "enroll_path": plan.enroll_path,
+            }
+            dest.writestr(f"{root}/enrollment.json", json.dumps(payload, indent=1))
+    return out.getvalue()