One access policy from content; onboarding into Kanidm as a form

Who may do what to what was five checks in five files: `qualifies` on
a page, `requires_group`/`public` on a resource, a desk's transition
allow-list, a self_transition's email check, the automation token.
They are now compiled from content on every load into one Cedar
policy set (src/access.rs), and every server entry point asks it: open
and submit a page, read a resource, move a record, fire a self
transition, read a bucket as the automation service, extend an
invite. Each decision names the rules that granted it; refusals and
every mutation are published on portal.access.decided, and
portal.access.<site>.may answers the same question for other apps
over request-reply (proven live against uhhm's content). The policy
validates against a fixed schema, so a content shape the compiler
cannot express fails instead of granting nothing. Identity is still
Kanidm's; the browser keeps is_qualified as a rendering hint only.

`invite: {group}` on an alternative of a gated page onboards a person:
src/people.rs creates the account, records the email, adds the group
and mints a one-time credential link through Kanidm's REST API with a
service-account token (KANIDM_API_TOKEN, in idm_people_on_boarding).
The result is recorded with the answer into the runtime's
portal_invites bucket and announced on portal.people.invited. Validated:
an invite needs a gated page and required name and email fields.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01L4jrCgLiKKHAEFuZUJjckH

Cargo.toml

@@ -38,6 +38,7 @@ uuid = { version = "1", features = ["v4", "serde"], optional = true }
 dotenvy = { version = "0.15", optional = true }
 anyhow = { version = "1", optional = true }
 futures = { version = "0.3", optional = true }
+cedar-policy = { version = "4", optional = true }
 tracing = { version = "0.1", optional = true }
 tracing-subscriber = { version = "0.3", features = ["env-filter"], optional = true }
 # jq-filter evaluation for ResourceSource's optional `jq` field
@@ -96,6 +97,7 @@ ssr = [
     "dep:dotenvy",
     "dep:anyhow",
     "dep:futures",
+    "dep:cedar-policy",
     "dep:tracing",
     "dep:tracing-subscriber",
     "dep:jaq-core",