feat(studio): plain-language ask bar + collapsible filter + AI search (v0.32.0)

Three changes against the user feedback "der text ist zu
zerhackt, die filter-leiste nimmt zu viel sicht weg, llm-suche
wenn das geht":

1. Today-Hero copy rewritten in flowing prose. The fallback
   story drops the code-fence templates ("`mcp.<server>.<tool>`")
   and reads as a single arc per language. Same trust model,
   gentler register.

2. Filter row collapses behind a single `_FilterButton` with a
   "Filter · N active" count badge. Status / Source / Installed
   chips now live inside `_FilterDialog` — invisible until the
   operator wants them, recovers a full row of viewport. The
   category strip stays inline because category is the most
   common cut and benefits from being one click away.

3. New `_AskBar` replaces the old single-line `_SearchField`:

   - Multi-line input (1-4 lines auto-grow) so questions don't
     overflow horizontally.
   - Cmd+Enter / Ctrl+Enter submits; bare Enter inserts a
     newline so the operator can write multi-line questions
     naturally.
   - Heuristic question detector (ends in `?` or ≥4 words)
     routes the submit to the System-AI's askAi RPC instead of
     the substring search. Live keystrokes still keyword-search
     for short queries; question-shaped input holds the grid
     steady until submit so the visible result set doesn't
     wipe with every space.
   - The LLM is asked for a strict-JSON ranking of up to 5
     modules with a one-phrase reason each. Unknown module
     names are dropped silently — operators must not see
     hallucinated entries.
   - The new `_AiAnswerCard` renders the LLM's answer plus the
     ranked match list above the grid; the grid filters to
     just those names so the answer and the visible cards
     stay coherent. Clearing the question collapses everything
     back.
   - Falls back to plain keyword search when System AI is off
     (with an explanatory hint instead of the AI hint).

The AI path uses the System-AI the operator already configured
in Settings; same privacy mode, same audit-log trail. Nothing
new leaves the hub.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/l10n/app_localizations_en.dart

@@ -318,6 +318,62 @@ class AppLocalizationsEn extends AppLocalizations {
   String get storeSearchHint =>
       'Search modules — name, tagline, tag, capability…';
 
+  @override
+  String get storeAskHint =>
+      'What do you need? Try \"a module that reads tabular data\" or just type a keyword.';
+
+  @override
+  String get storeAskSubmit => 'Search';
+
+  @override
+  String get storeAskAi => 'Ask the AI';
+
+  @override
+  String get storeAskClear => 'Clear question';
+
+  @override
+  String get storeAskAiThinking => 'Looking through modules…';
+
+  @override
+  String get storeAskAiUnavailable =>
+      'Configure a System AI in Settings to ask questions in plain language.';
+
+  @override
+  String get storeAskNoMatches =>
+      'No matches yet — refine the question or browse the grid below.';
+
+  @override
+  String get storeAskAnswerLabel => 'AI suggestion';
+
+  @override
+  String get storeAskAnswerWhy => 'Why this matches';
+
+  @override
+  String get storeAskMatchPill => 'match';
+
+  @override
+  String get storeFilterLabel => 'Filter';
+
+  @override
+  String storeFilterActiveCount(int n) {
+    return '$n active';
+  }
+
+  @override
+  String get storeFilterReset => 'Reset filters';
+
+  @override
+  String get storeFilterApply => 'Done';
+
+  @override
+  String get storeFilterStatusGroup => 'Status';
+
+  @override
+  String get storeFilterSourceGroup => 'Source';
+
+  @override
+  String get storeFilterInstalledGroup => 'Show only installed';
+
   @override
   String get storeFeatured => 'FEATURED';