Archive demo-activity-bot, pg-boss-background-jobs, configurable-demo-persona

Fold completed deltas into main specs (activity-feed, route-management,
infrastructure, planner-session), add new background-jobs and
demo-activity-bot capability specs, and move the three change dirs to
openspec/changes/archive/.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

openspec/specs/activity-feed/spec.md

@@ -113,3 +113,18 @@ Creating an activity with `visibility = 'public'` SHALL enqueue a fan-out job th
 #### Scenario: No accepted followers means no notifications
 - **WHEN** a user with zero accepted followers creates a public activity
 - **THEN** the fan-out job runs and inserts zero rows
+
+### Requirement: Synthetic activity flag
+The Journal SHALL persist a `synthetic` boolean on every activity so automated / demo content can be distinguished from user-created content.
+
+#### Scenario: User-created activities default to non-synthetic
+- **WHEN** an activity is created through any user-facing flow (GPX upload, sync import, Planner handoff)
+- **THEN** the activity row is persisted with `synthetic = false`
+
+#### Scenario: Bot inserts flag their rows as synthetic
+- **WHEN** the demo-activity-bot inserts an activity
+- **THEN** the row is persisted with `synthetic = true`
+
+#### Scenario: Synthetic flag is not user-editable
+- **WHEN** an activity owner edits the activity via any user-facing action
+- **THEN** the stored `synthetic` value is not changed by the edit