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>

lib/api/__tests__/schemas.test.ts

@@ -69,7 +69,7 @@ import {
 } from '../schemas'
 
 // ============================================================
-// Helpers — minimal valid objects for composition
+// Helpers: minimal valid objects for composition
 // ============================================================
 
 const validUuid = '550e8400-e29b-41d4-a716-446655440000'
@@ -401,7 +401,7 @@ describe('UpdateInvoiceSchema', () => {
     expect(result.success).toBe(false)
   })
 
-  it('drops save_as_draft — editing a draft never re-creates it', () => {
+  it('drops save_as_draft: editing a draft never re-creates it', () => {
     const result = UpdateInvoiceSchema.safeParse(validInvoice({ save_as_draft: true }))
     expect(result.success).toBe(true)
     if (result.success) {
@@ -1589,7 +1589,7 @@ describe('CreateDeadlineSchema', () => {
       deadline_type: 'tax',
       due_time: '25:00',
     })
-    // Note: regex accepts 25:00 — business logic validates actual time values
+    // Note: regex accepts 25:00: business logic validates actual time values
     // This test documents the current behavior
     const parsed = CreateDeadlineSchema.safeParse({
       title: 'Test',

lib/api/__tests__/validate.test.ts

@@ -191,7 +191,7 @@ describe('validateQuery', () => {
 
     expect(result.success).toBe(false)
     if (!result.success) {
-      // The response is a NextResponse — we verify it's a 400
+      // The response is a NextResponse: we verify it's a 400
       expect(result.response.status).toBe(400)
     }
   })