Filter panel results by project and hide test code

Roadmap item 3. One Filters button opens a menu holding both, rather than
two more controls in a toolbar that is already crowded in a docked panel:

- Hide test code, with the count of test results.
- A checkbox per project with its result count, plus All / None.

The button shows how many filters are active and the summary line reads
"12 of 43 references" while anything is filtered. Projects are persisted as
an *exclusion* list, so a project that only appears in a later search shows
up instead of being silently hidden. Test hiding seeds from
coloredReferences.hideTests on first results, then follows the panel.

What counts as test code is coloredReferences.testPattern, a regular
expression matched against the workspace-relative path and against the
containing project name. Matching on names turned out to need care: the
first pattern classified Latest.cs as a test because "Latest" contains
"test". The built-in pattern now requires the name to start at a boundary,
or an uppercase T for the CamelCase FooTests.cs form, and covers test/tests
directories, Tests.cs, foo_test.go, test_foo.py, foo.spec.ts and projects
named Something.Tests. An invalid configured regex is reported once and
ignored rather than throwing per search.

These filters narrow the panel only; the editor view still lists everything.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -11,8 +11,8 @@ highlighted like search matches; **writes are bold** on the theme's stronger wri
 same colour the editor itself uses for a write.
 
 **Panel view** shows the same results as a table with resizable, sortable columns — Code, File, Line, Kind,
-Project and Containing member — grouped by file, with a filter box and a reads/writes filter. By default it
-docks in the **bottom panel**
+Project and Containing member — grouped by file, with a text filter plus filters for reads/writes, project and
+test code. By default it docks in the **bottom panel**
 alongside Terminal and Problems, where a wide, short table reads best; you can drag it to either side bar,
 or set `coloredReferences.panelLocation` to put it in an editor group instead.
 
@@ -36,6 +36,19 @@ The **All / Reads / Writes** buttons filter by kind, and the summary line counts
 the text filter, so typing `write` narrows to writes as well. See *Known limitations* for where the kind comes
 from.
 
+**Filters** opens a menu to hide test code or to include only some projects, each with its result count. The
+button shows how many filters are active, and the summary line reads *"12 of 43 references"* while anything is
+filtered. Choices persist per panel, and projects are remembered as an *exclusion* list — a project that only
+turns up in a later search shows up rather than being silently hidden.
+
+What counts as test code is a regular expression, `coloredReferences.testPattern`, matched against each
+result's workspace-relative path and against its containing project name. The built-in pattern covers
+`test`/`tests` directories, `FooTests.cs`, `Tests.cs`, `foo_test.go`, `test_foo.py`, `foo.spec.ts` and projects
+named `Something.Tests` — without catching names that merely contain the word, like `Latest.cs` or a `contest`
+directory. `coloredReferences.hideTests` sets whether the filter starts on.
+
+These filters narrow what the panel shows; the editor view always lists every reference.
+
 ## Semantic tokens
 
 VS Code colors code twice: a TextMate grammar handles keywords, strings and comments from the text alone, then
@@ -63,6 +76,9 @@ grammar-only colouring; results spanning more than 40 files skip it.
 - `coloredReferences.openBeside` — open results beside the current editor (default `true`)
 - `coloredReferences.showProject` — show the containing project in file headers (default `true`)
 - `coloredReferences.reuseTab` — reuse one results tab/panel instead of opening a new one per search (default `true`)
+- `coloredReferences.hideTests` — start the panel with test code hidden (default `false`)
+- `coloredReferences.testPattern` — regular expression deciding what counts as test code; empty uses the
+  built-in pattern
 
 ## Install
 
@@ -107,6 +123,6 @@ the expected results stay deterministic.
 1. ~~Webview panel with resizable, sortable columns~~ — done; missing: virtualized rendering for very large
    result sets, and remembering column layout per workspace rather than per panel
 2. ~~Semantic token overlay~~ — done in both views
-3. Filter by project / exclude tests
+3. ~~Filter by project / exclude tests~~ — done in the panel
 4. ~~Read/write kind~~ — done in both views