feat(perf): implement performance optimizations for session handling

- Introduced a new configuration file `config.yaml` for specifying project context and artifact rules.
- Added `.openspec.yaml` files for tracking changes related to performance improvements.
- Created design documents outlining the context, goals, decisions, and migration plans for optimizing session performance.
- Proposed changes include batching database queries, debouncing event refreshes, purging old events, and implementing loading states for better user experience.
- Added tasks and specifications to ensure proper implementation and validation of the new features.

These enhancements aim to improve the scalability and responsiveness of the application during collaborative sessions.

openspec/changes/archive/2026-03-09-perf-quick-wins/specs/perf-loading-states/spec.md

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+## ADDED Requirements
+
+### Requirement: Loading skeleton on main routes
+The application SHALL display a skeleton loading state during navigation to `/sessions`, `/weather`, and `/users` routes, activated by Next.js App Router streaming via `loading.tsx` files.
+
+#### Scenario: Navigation to sessions page shows skeleton
+- **WHEN** a user navigates to `/sessions`
+- **THEN** a loading skeleton SHALL be displayed immediately while the page data loads
+
+#### Scenario: Navigation to weather page shows skeleton
+- **WHEN** a user navigates to `/weather`
+- **THEN** a loading skeleton SHALL be displayed immediately while the page data loads
+
+#### Scenario: Navigation to users page shows skeleton
+- **WHEN** a user navigates to `/users`
+- **THEN** a loading skeleton SHALL be displayed immediately while the page data loads
+
+### Requirement: Modal lazy loading
+Heavy modal components (ShareModal) SHALL be loaded lazily via `next/dynamic` to reduce the initial JS bundle size.
+
+#### Scenario: ShareModal not in initial bundle
+- **WHEN** a page loads that contains a ShareModal trigger
+- **THEN** the ShareModal component code SHALL NOT be included in the initial JS bundle
+- **THEN** the ShareModal code SHALL be fetched only when first needed