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.dart

@@ -620,6 +620,108 @@ abstract class AppLocalizations {
   /// **'Search modules — name, tagline, tag, capability…'**
   String get storeSearchHint;
 
+  /// No description provided for @storeAskHint.
+  ///
+  /// In en, this message translates to:
+  /// **'What do you need? Try \"a module that reads tabular data\" or just type a keyword.'**
+  String get storeAskHint;
+
+  /// No description provided for @storeAskSubmit.
+  ///
+  /// In en, this message translates to:
+  /// **'Search'**
+  String get storeAskSubmit;
+
+  /// No description provided for @storeAskAi.
+  ///
+  /// In en, this message translates to:
+  /// **'Ask the AI'**
+  String get storeAskAi;
+
+  /// No description provided for @storeAskClear.
+  ///
+  /// In en, this message translates to:
+  /// **'Clear question'**
+  String get storeAskClear;
+
+  /// No description provided for @storeAskAiThinking.
+  ///
+  /// In en, this message translates to:
+  /// **'Looking through modules…'**
+  String get storeAskAiThinking;
+
+  /// No description provided for @storeAskAiUnavailable.
+  ///
+  /// In en, this message translates to:
+  /// **'Configure a System AI in Settings to ask questions in plain language.'**
+  String get storeAskAiUnavailable;
+
+  /// No description provided for @storeAskNoMatches.
+  ///
+  /// In en, this message translates to:
+  /// **'No matches yet — refine the question or browse the grid below.'**
+  String get storeAskNoMatches;
+
+  /// No description provided for @storeAskAnswerLabel.
+  ///
+  /// In en, this message translates to:
+  /// **'AI suggestion'**
+  String get storeAskAnswerLabel;
+
+  /// No description provided for @storeAskAnswerWhy.
+  ///
+  /// In en, this message translates to:
+  /// **'Why this matches'**
+  String get storeAskAnswerWhy;
+
+  /// No description provided for @storeAskMatchPill.
+  ///
+  /// In en, this message translates to:
+  /// **'match'**
+  String get storeAskMatchPill;
+
+  /// No description provided for @storeFilterLabel.
+  ///
+  /// In en, this message translates to:
+  /// **'Filter'**
+  String get storeFilterLabel;
+
+  /// No description provided for @storeFilterActiveCount.
+  ///
+  /// In en, this message translates to:
+  /// **'{n} active'**
+  String storeFilterActiveCount(int n);
+
+  /// No description provided for @storeFilterReset.
+  ///
+  /// In en, this message translates to:
+  /// **'Reset filters'**
+  String get storeFilterReset;
+
+  /// No description provided for @storeFilterApply.
+  ///
+  /// In en, this message translates to:
+  /// **'Done'**
+  String get storeFilterApply;
+
+  /// No description provided for @storeFilterStatusGroup.
+  ///
+  /// In en, this message translates to:
+  /// **'Status'**
+  String get storeFilterStatusGroup;
+
+  /// No description provided for @storeFilterSourceGroup.
+  ///
+  /// In en, this message translates to:
+  /// **'Source'**
+  String get storeFilterSourceGroup;
+
+  /// No description provided for @storeFilterInstalledGroup.
+  ///
+  /// In en, this message translates to:
+  /// **'Show only installed'**
+  String get storeFilterInstalledGroup;
+
   /// No description provided for @storeFeatured.
   ///
   /// In en, this message translates to: