Fix #7442: REST collections, ResourceEditor, Clear response

[Panthevm]

Addresses items from HealthSamurai/sansara#7442.

Summary

Collections sidebar

• New top-level "Create" button — copies the active tab into a fresh collection.
• Save now resolves the snippet by tab.historyId ?? tab.id and binds the editor tab to the snippet id, so subsequent edits update the existing sidebar entry (the sidebar method/path now updates after Save, no more orphaned duplicates).
• Rename via the row menu: deferred startRenaming (the dropdown no longer steals focus and aborts the rename); folders are force-expanded before rename so children stay visible; stopPropagation on the menu item click.
• Rename input: onBlur commits non-empty values via tree.completeRenaming() and reverts empty input via tree.abortRenaming() (instead of always aborting on click-outside).
• TreeView remounts on data update so saved edits show up immediately; folder collapsed state is carried over to the new title on rename so closed folders stay closed.

ResourceEditor

• Propagates resourceType to HSComp.CodeEditor as resourceTypeHint through EditTabContent → EditorTab. FHIR validator now resolves the StructureDefinition correctly and stops marking valid properties (e.g. nested extension) as "Unknown property".

REST response panel

• New "Clear response" button (X) at the right edge of the response header — deletes the stored response for the current tab; the pane falls back to the empty "No response yet" placeholder.

Out of scope

• Item 5 ("pagination without total") — to be addressed separately.

Test plan

• Collections: create a request → click "Create" → new collection appears with the active tab inside.
• Collections: load a saved snippet → change method → Save → sidebar item method updates in place (no duplicate row).
• Collections: collapse a folder → rename it from the row menu → folder stays collapsed; children are not visible after rename.
• Collections: rename a snippet → click outside the input → name commits; rename then clear input → click outside → name reverts.
• ResourceEditor: open a Patient or other resource with extension nested inside a backbone (e.g. identifier[].extension) → no "Unknown property" diagnostic.
• REST: send a request, get a response → click the X button at the far right of the response header → response is cleared, pane shows "No response yet".