style: remove em/en dashes repo-wide, add CLAUDE.md rule against them (#890)

Em dashes (—) and en dashes (–) had spread across comments, docs, tests,
and a few UI strings, reading as AI-generated boilerplate rather than
house style. Replaced each with punctuation matching its context: colon
for explanatory clauses, comma for asides, plain hyphen for numeric/legal
ranges (e.g. "21-23§"), "to"/"till" for date ranges, parentheses for
paired-dash asides. messages/en.json and messages/sv.json were fixed by
hand together to keep sv/en in sync.

Left untouched where the dash is the functional subject rather than
decorative punctuation: date-range-parser.ts's separator regex,
charset-repair.ts's CP1252 byte-mapping table (and its test), the SIE
encoding mojibake docs, generic-csv.ts's minus-sign normalizer, the
agent system-prompt files that already instruct against em dashes, and
a golden iXBRL test fixture compared byte-for-byte.

Also fixes two bugs surfaced along the way: an off-by-one in
ApiKeysPanel's scope-label split (a leftover from an earlier partial
pass), and a charset-repair test that had lost the literal en-dash it
exists to verify.

Regenerated the agent atom seed migration (skills:generate) since 27
SKILL.md files changed. Added a CLAUDE.md rule against em/en dashes,
with an explicit carve-out for the functional-dash cases above.

Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>

.env.example

@@ -29,10 +29,10 @@ CRON_SECRET=generate-a-random-secret
 # User-Key is entered by the user in the migration wizard)
 # BJORN_LUNDEN_CLIENT_ID=
 # BJORN_LUNDEN_CLIENT_SECRET=
-# Bolagsverket — digital inlämning av årsredovisning (bolagsverket extension).
+# Bolagsverket: digital inlämning av årsredovisning (bolagsverket extension).
 # BOLAGSVERKET_ENV is test | accept | prod (default test) and also caps which
 # environment a company may select in settings (test < accept < prod).
-# Certificate material is read from env ONLY (PEM or base64-wrapped PEM) —
+# Certificate material is read from env ONLY (PEM or base64-wrapped PEM):
 # never from extension settings or the database.
 #
 # SECRET CUSTODY (prod): never keep the real mTLS private key in a plaintext
@@ -41,7 +41,7 @@ CRON_SECRET=generate-a-random-secret
 # the deploy pipeline, and rotate the client certificate/key on the cadence
 # agreed with Bolagsverket (and immediately on suspected exposure). Outbound
 # hosts are pinned per environment in extensions/general/bolagsverket/lib/
-# client.ts (HOSTS) — the endpoint is not configurable via env.
+# client.ts (HOSTS): the endpoint is not configurable via env.
 # BOLAGSVERKET_ENV=
 # BOLAGSVERKET_CLIENT_CERT=
 # BOLAGSVERKET_CLIENT_KEY=