ci(codeql): rewire local model pack discovery — fix 1122f5a silent no-op

Two CodeQL runs (commits 1122f5a + c4157fd) since the initial Option A
landing both completed with conclusion=success but failed to dismiss
alert #23 (go/request-forgery on scep_probe.go:232). Root cause: the
local pack never loaded.

The bug was in codeql-config.yml — `packs: { go: ['./'] }` looked
plausible (the path is relative to the config file's directory) but
the `packs:` field requires pack NAMES, not paths. Discovery of
unpublished local packs goes through the codeql-action `init` step's
`additional-packs:` input, not through `packs:`.

Verified pattern by reading github/vscode-codeql's working
.github/codeql/ setup. The supported chain:

   workflow init step      passes additional-packs: <parent-dir>
                                        ↓
       CodeQL CLI           registers each pack under the parent
                                        ↓
   codeql-config.yml        names the pack in `packs: go: [name]`
                                        ↓
       CodeQL CLI           resolves the name → pack on disk
                                        ↓
   pack's qlpack.yml        declares extensionTargets: codeql/go-all
                                        ↓
   data extension YAML      auto-loads, applies the barrier rows

Restructure to match this chain:

  Before                                    After
  --------                                  -----
  .github/codeql/qlpack.yml                .github/codeql/codeql-config.yml
  .github/codeql/models/                   .github/codeql/certctl-models/
    request-forgery-sanitizers.model.yml     qlpack.yml
  .github/codeql/codeql-config.yml           models/
                                               request-forgery-sanitizers.model.yml

The new `.github/codeql/certctl-models/` is the pack directory, named
to match `name: shankar0123/certctl-models` in qlpack.yml. Its parent
`.github/codeql/` is what additional-packs points at. The action
discovers the pack by walking the parent dir, sees the qlpack.yml,
registers the name, and `packs:` lookup succeeds.

Three concrete changes:

  - Pack moves from .github/codeql/{qlpack.yml, models/} into the
    sibling subdirectory .github/codeql/certctl-models/.

  - codeql-config.yml's packs: directive now uses the pack NAME
    (`shankar0123/certctl-models`) instead of the broken `./` path.

  - codeql.yml's Initialize CodeQL step gains
    `additional-packs: .github/codeql` so the CLI's resolver knows
    where to find unpublished packs.

Belt-and-suspenders correctness fix: the model row's `subtypes`
column now uses `False` (Python-style capitalized) instead of `false`
to match every shipped CodeQL Go .model.yml convention. SnakeYAML
accepts lowercase too — this is a hedge against any strict-format
tooling in the path.

Why this matters: alert #23 is rated Critical with CWE-918 + CWE-180.
The runtime defense is correct (validate-then-pin via
ValidateSafeURL + SafeHTTPDialContext), but the analyzer doesn't
know it. With the pack actually loading this time, the next CodeQL
run will see the barrier and dismiss the alert at source. Same fix
implicitly applies to the webhook notifier's outbound client.Do
(the second site that uses ValidateSafeURL).

Operator: push and watch the next CodeQL run dismiss alert #23. If
it doesn't, the next iteration will be on the YAML row's column
shape — most likely a one-line tweak, not another redesign.

.github/codeql/certctl-models/models/request-forgery-sanitizers.model.yml

@@ -0,0 +1,61 @@
+# Models-as-Data sanitizer rows for the go/request-forgery query.
+#
+# Each row in `data` is a 9-tuple matching the `barrierModel` extensible
+# predicate signature for Go:
+#
+#   (package, type, subtypes, name, signature, ext, output, kind, provenance)
+#
+# Where:
+#   - package    — Go import path of the sanitizer
+#   - type       — receiver type ("" for package-level functions)
+#   - subtypes   — false for non-method functions; true to apply to subtypes
+#   - name       — function/method name
+#   - signature  — empty for Go (the column is not used)
+#   - ext        — empty (reserved)
+#   - output     — access path that becomes the barrier; "Argument[N]" means
+#                  the Nth argument is sanitized after the call
+#   - kind       — taint kind the barrier applies to ("request-forgery" for
+#                  the go/request-forgery query)
+#   - provenance — origin tag for the model row ("manual" — hand-authored)
+#
+# References:
+#   - https://codeql.github.com/docs/codeql-language-guides/customizing-library-models-for-go/
+#   - https://github.blog/changelog/2026-04-21-codeql-now-supports-sanitizers-and-validators-in-models-as-data/
+
+extensions:
+  # ---------------------------------------------------------------------------
+  # validation.ValidateSafeURL — primary egress URL validator.
+  # ---------------------------------------------------------------------------
+  # Signature: func ValidateSafeURL(rawURL string) error
+  #
+  # Rejects (returns non-nil error for):
+  #   - non-http/https schemes (file://, gopher://, ftp://, data:, etc.)
+  #   - URLs missing a host
+  #   - literal-IP hosts in: 127/8 + ::1 (loopback), 169.254.0.0/16 (link-
+  #     local incl. AWS/Azure/GCP cloud metadata at 169.254.169.254),
+  #     224.0.0.0/4 + ff00::/8 (multicast), 255.255.255.255 (broadcast),
+  #     0.0.0.0 + :: (unspecified), fe80::/10 (IPv6 link-local)
+  #   - DNS names whose A/AAAA resolution returns any IP in the set above
+  #
+  # Source of truth: internal/validation/ssrf.go (ValidateSafeURL +
+  # IsReservedIP + isReservedIPForDial). RFC 1918 (10/8, 172.16/12,
+  # 192.168/16) is intentionally NOT blocked — see the comment block at
+  # ssrf.go:17-21 for the design rationale.
+  #
+  # The companion runtime defense is SafeHTTPDialContext (installed on the
+  # http.Transport via http.Transport.DialContext) which re-resolves the
+  # host at dial time and pins the dial to a literal non-reserved IP,
+  # defeating DNS rebinding. SafeHTTPDialContext returns a closure rather
+  # than acting as a direct sanitizer in dataflow terms, so it isn't
+  # modeled here — but ValidateSafeURL alone is sufficient to dismiss the
+  # request-forgery alerts at the call sites that use it (scep_probe.go,
+  # webhook.go).
+  - addsTo:
+      pack: codeql/go-all
+      extensible: barrierModel
+    data:
+      # subtypes uses Python-style `False` (capitalized) to match every
+      # shipped CodeQL Go .model.yml — see e.g. github/codeql/go/ql/lib/ext/
+      # database.sql.model.yml. SnakeYAML accepts lowercase too, but
+      # capitalized matches the canonical convention.
+      - ["github.com/shankar0123/certctl/internal/validation", "", False, "ValidateSafeURL", "", "", "Argument[0]", "request-forgery", "manual"]