fix(snowflake): unblock multi-schema ingest and relationship discovery (#204)

* feat(setup): drop redundant Snowflake schema prompt; fall back to free-text on listSchemas failure

Snowflake setup previously asked for a single schema as free text, then
ran a multiselect against the discovered schemas — two schema questions
back-to-back, with the first being only a session bootstrap. The SDK's
`schema` is optional, so the bootstrap step is unnecessary.

- Remove the free-text Snowflake schema prompt; only pass `schema` to
  snowflake-sdk when one is configured.
- When `listSchemas()` fails (e.g. role lacks SHOW SCHEMAS), prompt the
  user for a comma-separated list, persist it as `schema_names`, and use
  it as both the table-list filter and the multiselect default. Applies
  to every driver with a scope-discovery spec, not just Snowflake.
- Update docs to lead with `schema_names`; keep `schema_name` as a
  documented single-schema shorthand.

* fix(snowflake): keep introspecting when primary-key discovery is denied

The PK query joins INFORMATION_SCHEMA.TABLE_CONSTRAINTS and
INFORMATION_SCHEMA.KEY_COLUMN_USAGE, which require grants the
connection role may not have. Previously a 'SQL compilation error:
Object ANALYTICS.INFORMATION_SCHEMA.KEY_COLUMN_USAGE does not exist
or not authorized' aborted the entire introspect — schemas, columns,
and row counts were all discarded over a missing nice-to-have.

Wrap the constraint query in try/catch, log a one-line warning per
schema, and return an empty PK map. Columns end up with
primaryKey=false; relationship inference still has FK and profiling
to fall back on.

* fix(scan): unblock relationship discovery on Snowflake

Two adjacent bugs prevented the scan's relationship pipeline from producing
any joins on a Snowflake warehouse:

- relationship-profiling.ts fell through to a default `GROUP_CONCAT` branch
  for unknown drivers. Snowflake has no GROUP_CONCAT, so every per-table
  profile query failed with "Unknown function GROUP_CONCAT". Add an explicit
  Snowflake branch that uses LISTAGG with a literal '\x1f' delimiter
  (Snowflake requires the delimiter to be a constant, so CHR(31) is rejected).
- description-generation.ts destructured `connector.sampleTable` and
  `connector.sampleColumn` into bare locals, losing the `this` binding when
  the class-method connectors (Snowflake, Postgres, MySQL) were invoked.
  Every sample call threw "Cannot read properties of undefined (reading
  'assertConnection')" and degraded LLM descriptions to metadata-only
  prompts. Call the methods through the connector instead.

Without these, even after the primary-key probe is allowed to fail softly,
the scan ends up with 0 validated relationships and an empty `joins:` block
in every shard YAML.

* test(scan): cover table-ref helpers

* feat(scan): plumb tableScope through live-database introspection port

* feat(scan): apply tableScope during metadata fetch

* feat(scan): enforce table scope at fetch boundary

* feat(scan): pool Snowflake sessions and batch enrichment for faster ingest (#206)

* feat(cli): add RSA key-pair auth option to Snowflake setup wizard

Extends the interactive Snowflake setup flow with an authentication-method
prompt (password vs RSA/JWT key-pair). The RSA branch collects a private-key
path (env/file/absolute) and an optional passphrase; the resulting connection
config records `authMethod: 'rsa'` with `privateKey` and `passphrase` instead
of `password`.

* feat(scan): pool Snowflake sessions

* fix(scan): reuse structural snapshots and cleanup connectors

* feat(scan): parallelize relationship profiling

* feat(scan): batch table description generation

* docs: document Snowflake ingest concurrency knobs

* fix(scan): close Snowflake ingest perf verification gaps

* fix(scan): keep batched description failure bounded

* feat(scan): dispatch query-history probes by connection driver

Extract historic-sql dialect resolution into a shared helper so the
status-project readiness check and the local ingest factory agree on
which connections enable query history and which probe to run. The
status command now picks the postgres/snowflake/bigquery probe based on
the connection's driver instead of always reporting against postgres,
which previously caused snowflake connections with queryHistory.enabled
to surface a misleading "driver is snowflake" failure.

Also drops a noisy console.warn from Snowflake primary-key discovery —
INFORMATION_SCHEMA.KEY_COLUMN_USAGE is commonly ungranted for read-only
roles and the FK + profiling paths handle the empty PK map already.

* fix(llm): allow StructuredOutput tool and raise maxTurns for generateObject

The Claude Code agent SDK announces an internal pseudo-tool named
StructuredOutput in the system/init message whenever outputFormat is set
to { type: 'json_schema' }. The runtime's isolation check built its
allowedToolIds set only from MCP tool ids and treated StructuredOutput
as an unexpected host-injected tool, so every generateObject call threw
"Claude Code runtime isolation failed: tools=StructuredOutput ..." and
the table-descriptions and relationship-LLM-proposal enrichment stages
recorded null output across the board.

Whitelist StructuredOutput specifically in generateObject's
allowedToolIds — the check also enforces missing_tools symmetry, so
generateText and runAgentLoop, which do not see StructuredOutput, must
not require it.

generateObject also ran with maxTurns: 1, which the model intermittently
breached when it emitted thinking text before the structured response.
Raised to 5 to give the schema-bound call enough headroom without
allowing unbounded loops. The existing tests now exercise the path with
an init message that announces StructuredOutput so the regression cannot
slip back in.

* chore(scripts): add ktx-reset.sh project-cleanup helper

Convenience script for repeatable ingest testing: takes a project
directory and prunes everything except ktx.yaml and .ktx/secrets/, so
the next ktx setup or ktx ingest run starts from a known-clean state.

packages/cli/src/context/scan/table-ref.ts

@@ -0,0 +1,53 @@
+import type { KtxTableRef } from './types.js';
+
+/**
+ * Branded canonical string representation of a {@link KtxTableRef}.
+ *
+ * Connectors compare scopes for set membership via these keys instead of the
+ * raw object (JS `Set<object>` uses identity equality, which would be useless
+ * here). Build a key with {@link tableRefKey} and decode with
+ * {@link tableRefFromKey}.
+ */
+export type KtxTableRefKey = string & { readonly __brand: 'KtxTableRefKey' };
+
+const SEPARATOR = '\x1f';
+
+/** @internal */
+export function tableRefKey(ref: KtxTableRef): KtxTableRefKey {
+  return `${ref.catalog ?? ''}${SEPARATOR}${ref.db ?? ''}${SEPARATOR}${ref.name}` as KtxTableRefKey;
+}
+
+/** @internal */
+export function tableRefFromKey(key: KtxTableRefKey): KtxTableRef {
+  const [catalog = '', db = '', name = ''] = key.split(SEPARATOR);
+  return {
+    catalog: catalog.length > 0 ? catalog : null,
+    db: db.length > 0 ? db : null,
+    name,
+  };
+}
+
+export function tableRefSet(refs: readonly KtxTableRef[]): ReadonlySet<KtxTableRefKey> {
+  return new Set(refs.map(tableRefKey));
+}
+
+/**
+ * Return the bare table names from a scope that fall within the given
+ * (catalog, db) namespace. `catalog: null` is treated as a wildcard so that
+ * legacy 2-part `"db.name"` entries continue to match. Same for `db: null`.
+ */
+export function scopedTableNames(
+  scope: ReadonlySet<KtxTableRefKey>,
+  namespace: { catalog?: string | null; db?: string | null },
+): string[] {
+  const names = new Set<string>();
+  const wantCatalog = namespace.catalog ?? null;
+  const wantDb = namespace.db ?? null;
+  for (const key of scope) {
+    const ref = tableRefFromKey(key);
+    if (wantCatalog !== null && ref.catalog !== null && ref.catalog !== wantCatalog) continue;
+    if (wantDb !== null && ref.db !== null && ref.db !== wantDb) continue;
+    names.add(ref.name);
+  }
+  return [...names];
+}