Implements HttpFoldersStorage (CRUD over folders persisted in
state.yaml plus filesystem dirs) and HttpRequestsStorage (CRUD over
.md request files with frontmatter). Extends shared validation kinds
to cover 'request' for sibling-name conflict messages.

Adds HTTP environments and history storages on top of state.yaml,
exposes createHttpStorageProvider via useHttpStorage(), registers
HTTP space in PERSISTED_SPACE_IDS and integrates http runtime cache
into the markdown watcher so external file changes resync and
broadcast storage-synced.

…ts and history

…d history

Single source of truth for HTTP primitives shared between main, IPC and
renderer (renderer tsconfig already includes src/main/types/**). Removes
duplicate definitions from runtime/types.ts and inline declarations in
the IPC handler.

…nts, history and execute

Module-level reactive state for the HTTP space. Mirrors the notes-space
pattern: useHttpFolders/useHttpRequests/useHttpEnvironments/useHttpHistory
talk to the REST API, useHttpExecute wraps the spaces:http:execute IPC,
useHttpApp owns the cross-composable folderId/requestId selection.

useHttpRequests tracks a draft snapshot against the loaded request so the
UI can detect dirty state and offer save/discard. Adds the
spaces.http.untitledRequest i18n key for default request names.

HttpSpace view wires LayoutThreeColumn with HttpSidebar, RequestEditor and
ResponsePanel placeholders. useHttpSpaceInit kicks off folders/requests/
environments/history fetches once on mount. Real component bodies follow
in Phase 6.2-6.5.

…or pane

…utton)

…and row actions

…cription tab to pre-request

…nd drag-drop

…umentation