board: a tag in the prose is coloured where it sits, not printed twice

A tagged note was showing its tag twice — once where it was typed, once as a
chip — and the duplicate was the loud copy. Now the chip row carries only what
the body cannot say (a tag lifted off its own line, a label from the picker),
and a `#tag` left mid-sentence is tinted in place.

Which characters are a tag is asked of the CORE, the way the card already asks
it which lines are checklist items: `extract_tag_spans` keeps the spans
`extract_tags` throws away, and `body_tags` hands them to Kotlin. Offsets are
UTF-16 code units, because `AnnotatedString` and JS both index that way and a
char index lands mid-token the first time somebody writes an emoji. The web
keeps its own matcher in markdown.ts, mirroring `line_tags` case for case.

The inline ink is its own table, one Tailwind step deeper than the chip's. A
chip brings its own -100 fill and reads against that alone; inline text sits on
whatever the card is, including a gray-tagged card at neutral-200 — where the
chip's -700 measured 3.98 (green), 4.11 (orange) and 4.34 (teal), under the 4.5
body text needs. At -800/-300 every hue lands 5.63-12.01 light and 7.20-10.84
dark across every palette and generated fill.

Chips now carry the `#` on every surface. The via_tag branch that used to
decide it is gone from the card, and Android's row said no hash at all.

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

frontend/src/components/NoteEditor.vue

@@ -613,7 +613,10 @@ function revPreview(rev: NoteRevision): string {
             class="inline-flex items-center gap-1 rounded-full px-2 py-0.5 text-xs"
             :class="labelChip(lb)"
           >
-            {{ lb.via_tag ? "#" + lb.name : lb.name }}
+            <!-- `#` on every chip, matching the card. This row still lists the tags
+                 the BODY owns too — it is the control surface, and `via_tag` is what
+                 decides whether there is a cross to remove one with. -->
+            #{{ lb.name }}
             <button
               v-if="!lb.via_tag"
               type="button"