step 4: fresh kernel-only migrations

Deleted all 23+23 old chat-switchboard migration files.
Wrote 9+9 clean kernel-only migrations in postgres/ and sqlite/ subdirs.

27 tables per dialect covering all 20 store interfaces:
  001: users, refresh_tokens, policies, settings, presence, oidc
  002: teams, team_members, groups, group_members
  003: packages, package_user_settings, ext_permissions, ext_data_tables
  004: ext_connections, ext_dependencies, resource_grants
  005: notifications, notification_preferences
  006: audit_log
  007: workflows, workflow_stages, workflow_versions
  008: tasks, task_runs
  009: ws_tickets, rate_limit_counters

Dropped: providers, personas, channels, messages, knowledge, notes,
memory, workspaces, projects, folders, files, usage_log, tool_health,
workflow_assignments, ext_view_channels.

Schema changes vs old:
  - pgvector extension removed (no KB embeddings)
  - resource_grants: resource_type CHECK removed (open-ended)
  - workflow_stages: persona_id kept as nullable TEXT (no FK)
  - workflow_stages: stage_mode default=form_only, added custom
  - tasks: dropped output_channel_id, provider_config_id columns
  - tasks: task_type removed prompt, output_mode: notification|webhook|log
  - task_runs: dropped channel_id
  - platform_policies: kernel-only seeds
  - global_settings: kernel-only seeds, site name=Switchboard Core
  - Everyone group: kernel permissions (extension.use, workflow.submit)

-2815/+487 lines.

server/database/migrations/postgres/004_connections.sql

@@ -0,0 +1,66 @@
+-- ==========================================
+-- Switchboard Core — 004 Connections & Dependencies
+-- ==========================================
+
+CREATE TABLE IF NOT EXISTS ext_connections (
+    id          UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    type        TEXT NOT NULL,
+    package_id  TEXT NOT NULL,
+    scope       VARCHAR(10) NOT NULL
+                CHECK (scope IN ('global', 'team', 'personal')),
+    owner_id    TEXT NOT NULL DEFAULT '',
+    name        TEXT NOT NULL,
+    config      JSONB NOT NULL DEFAULT '{}'::jsonb,
+    is_active   BOOLEAN DEFAULT true,
+    created_at  TIMESTAMPTZ DEFAULT NOW(),
+    updated_at  TIMESTAMPTZ DEFAULT NOW(),
+    UNIQUE(type, scope, owner_id, name)
+);
+
+CREATE INDEX IF NOT EXISTS idx_ext_connections_type ON ext_connections(type);
+CREATE INDEX IF NOT EXISTS idx_ext_connections_scope ON ext_connections(scope);
+CREATE INDEX IF NOT EXISTS idx_ext_connections_owner ON ext_connections(owner_id) WHERE owner_id != '';
+CREATE INDEX IF NOT EXISTS idx_ext_connections_active ON ext_connections(is_active) WHERE is_active = true;
+
+DROP TRIGGER IF EXISTS ext_connections_updated_at ON ext_connections;
+CREATE TRIGGER ext_connections_updated_at BEFORE UPDATE ON ext_connections
+    FOR EACH ROW EXECUTE FUNCTION update_updated_at();
+
+-- ── Extension Dependencies ──────────────────
+
+CREATE TABLE IF NOT EXISTS ext_dependencies (
+    consumer_id  TEXT NOT NULL,
+    library_id   TEXT NOT NULL,
+    version_spec TEXT NOT NULL DEFAULT '>=0.0.0',
+    resolved_ver TEXT NOT NULL DEFAULT '0.0.0',
+    PRIMARY KEY (consumer_id, library_id),
+    FOREIGN KEY (consumer_id) REFERENCES packages(id) ON DELETE CASCADE,
+    FOREIGN KEY (library_id)  REFERENCES packages(id) ON DELETE RESTRICT
+);
+
+CREATE INDEX IF NOT EXISTS idx_ext_deps_consumer ON ext_dependencies(consumer_id);
+CREATE INDEX IF NOT EXISTS idx_ext_deps_library ON ext_dependencies(library_id);
+
+-- ── Resource Grants ─────────────────────────
+
+CREATE TABLE IF NOT EXISTS resource_grants (
+    id              UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    resource_type   VARCHAR(30) NOT NULL,
+    resource_id     UUID NOT NULL,
+    grant_scope     VARCHAR(20) NOT NULL DEFAULT 'team_only'
+                    CHECK (grant_scope IN ('team_only', 'global', 'groups')),
+    granted_groups  UUID[] NOT NULL DEFAULT '{}',
+    created_by      UUID NOT NULL REFERENCES users(id),
+    created_at      TIMESTAMPTZ DEFAULT NOW(),
+    updated_at      TIMESTAMPTZ DEFAULT NOW(),
+    UNIQUE(resource_type, resource_id)
+);
+
+CREATE INDEX IF NOT EXISTS idx_resource_grants_resource
+    ON resource_grants(resource_type, resource_id);
+CREATE INDEX IF NOT EXISTS idx_resource_grants_groups
+    ON resource_grants USING gin(granted_groups);
+
+DROP TRIGGER IF EXISTS resource_grants_updated_at ON resource_grants;
+CREATE TRIGGER resource_grants_updated_at BEFORE UPDATE ON resource_grants
+    FOR EACH ROW EXECUTE FUNCTION update_updated_at();