Foreign data wrapper options

Generated from extension/src/options.rs and extension/src/import.rs. Edit those files and run make docs-generate; CI fails on an uncommitted difference.

These are every option the validator accepts. An option not listed for a statement is rejected at DDL time, naming the statement and the offending option, rather than being ignored.

CREATE SERVER

CREATE SERVER ... OPTIONS — how to reach a gateway.

Option	Required	Default	Meaning
endpoint	yes	(none)	gateway address as an https URL, e.g. https://axiom-gateway:8443; plaintext is refused because the connection carries cluster data
ca_cert	no	the host trust store	path, readable by the Postgres server process, to the PEM CA bundle that signs the gateway certificate
rpc_timeout_secs	no	30	per-RPC deadline in whole seconds, greater than zero; a whole-cluster IMPORT FOREIGN SCHEMA can need more than the default

CREATE FOREIGN TABLE

CREATE FOREIGN TABLE ... OPTIONS — which kind a table maps to.

Option	Required	Default	Meaning
resource	yes	(none)	plural resource name, e.g. pods; sufficient on its own for the built-in kinds
group	no	"" (the core API group)	API group of the kind, e.g. apps or example.com
version	no	(none)	API version, e.g. v1; required together with kind for any kind that is not built in
kind	no	(none)	singular CamelCase kind, e.g. Widget; required together with version for any kind that is not built in
namespaced	no	true	whether the kind is namespaced; false makes the namespace column meaningless and it is omitted from generated DDL
writable	no	false for built-in read-only kinds, true otherwise	whether INSERT, UPDATE and DELETE are offered; cannot be turned on for kinds the extension keeps read-only, such as Pods
cache_mode	no	on_demand	on_demand serves every scan by RPC; watch serves scans from the watch-driven cache and starts a subscription for the kind

CREATE FOREIGN TABLE (column ... OPTIONS)

A foreign table column's OPTIONS — which field it maps to.

Option	Required	Default	Meaning
field	no	the top-level field whose name normalises to the column name	exact name of the top-level field the column reads and writes, e.g. stringData; only for columns that map to a top-level field

IMPORT FOREIGN SCHEMA

IMPORT FOREIGN SCHEMA ... OPTIONS — how a whole schema is generated.

Option	Required	Default	Meaning
cache_mode	no	on_demand	applied to every generated table, and silently downgraded to on_demand for a kind the API server will not let the gateway watch
prefix	no	"" (no prefix)	prepended to every generated table name, so two clusters can be imported into one schema without colliding

CREATE FOREIGN DATA WRAPPER and CREATE USER MAPPING

Neither accepts any option today, and both reject any that is given. The wrapper carries no configuration of its own, and per-caller credentials on a user mapping arrive in Phase 7 (see docs/AUTH.md).