Add browser search and richer URL matching

docs/browser-extension.md

@@ -93,6 +93,28 @@ Chromium / Chrome:
 - Username and password fields get an inline KeePassGO affordance that opens a candidate chooser anchored to the focused field and keeps fills scoped to that field's form when possible.
 - If a fill request needs user approval, the extension keeps the pending state visible in both the page affordance and the popup until KeePassGO resolves it, using the token-scoped pending-approval count from the local gRPC API.
 
+## Search And Matching
+
+User story:
+
+- When a page has no obvious match, the popup still lets the user search the
+  vault without leaving the browser.
+- Search results must stay scoped to what the current API token can actually
+  access.
+- Browser matching must treat common KeePass data conventions as real browser
+  targets, not just the primary `URL` field.
+
+Expected behavior:
+
+- The popup exposes a `Search Vault` field that queries KeePassGO directly.
+- Search results use the same fill path as page matches.
+- Search never leaks entries outside the token's authorized group scope.
+- A browser match can come from:
+  - the primary `URL` field
+  - scheme-less host values such as `gitlab.com`
+  - custom URL fields such as `URL1`, `URL2`, and similar KeePass-style URL
+    slots
+
 For extension-side regression checks, run:
 
 ```bash