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>

tests/pg/commit-method-provenance.pg.test.ts

@@ -9,7 +9,7 @@ import { getPool } from '@/tests/pg/setup'
 /**
  * Covers 20260618120001_commit_method_agent_provenance:
  *   - journal_entries.commit_method accepts the new 'agent' and 'api_key'
- *     values (MCP-relayed approvals — agent_first_vision.md §8 P0-1).
+ *     values (MCP-relayed approvals: agent_first_vision.md §8 P0-1).
  *   - The pre-existing values are still accepted.
  *   - Unknown values are still rejected by the CHECK constraint.
  *   - Exactly one commit_method constraint exists (guards against the
@@ -21,7 +21,7 @@ async function postWithCommitMethod(commitMethod: string): Promise<string> {
   const { userId, companyId, fiscalPeriodId } = await seedCompany()
   const entryId = await insertDraftJournalEntry({ userId, companyId, fiscalPeriodId })
   await insertBalancedLines(entryId)
-  // draft → posted with commit metadata — same transition the commit RPC does.
+  // draft → posted with commit metadata: same transition the commit RPC does.
   await getPool().query(
     `UPDATE public.journal_entries
        SET status = 'posted', voucher_number = 1, commit_method = $2
@@ -31,7 +31,7 @@ async function postWithCommitMethod(commitMethod: string): Promise<string> {
   return entryId
 }
 
-describe('journal_entries.commit_method — agent provenance values', () => {
+describe('journal_entries.commit_method: agent provenance values', () => {
   it.each(['agent', 'api_key', 'user_accept', 'bulk_accept'])(
     'accepts commit_method=%s',
     async (method) => {