fix(copy): replace em-dashes in user-facing strings with commas/periods

Per the project's no-dashes feedback rule (see CORBEL-Main memory
feedback_no_dashes.md), em-dashes in user-visible copy are the single
biggest "AI wrote this" surface tell. Forty-two occurrences across ten
files: ten in SettingsPage's group descriptions and option labels
(audio device picker, vocabulary help, prompt placeholders, model
descriptions), four in FirstRunPage's setup steps, three in
DictationPage / FilesPage / Energy chip tooltips, plus the privacy
bullets ("100% offline, no Python required, no cloud, no accounts,
no telemetry"), the rejection toast, MicroSteps thumb labels, and the
shutdown ritual prompts.

Replacement rule: subordinate-clause em-dashes followed by lowercase
become commas; sentence-break em-dashes followed by capitals become
full stops. Code comments left intact.

One non-em-dash regression caught while reviewing: TasksPage's energy
filter "no selection" placeholder showed "—" as a literal label; the
script changed it to a comma which read as a UI bug. Replaced with
"Any" instead.

src/lib/pages/ShutdownRitualPage.svelte

@@ -117,7 +117,7 @@
           <p class="text-[12px] text-text-secondary">Nothing in the list.</p>
         {:else}
           <p class="text-[11px] text-text-tertiary mb-3">
-            These are still here. Naming them silences the loop — you don't have to act now.
+            These are still here. Naming them silences the loop, you don't have to act now.
           </p>
           <ul class="flex flex-col gap-1">
             {#each openLoops.slice(0, 12) as task (task.id)}
@@ -146,7 +146,7 @@
           </li>
           <li>
             <span class="font-medium text-text">Pick a closing line.</span>
-            Say it out loud when you're ready — something like "I'm done for today."
+            Say it out loud when you're ready, something like "I'm done for today."
           </li>
           <li>
             <span class="font-medium text-text">Let it rest.</span>