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>

scripts/check-pg-test-coverage.mjs

@@ -6,22 +6,22 @@
  *
  * This enforces the rule documented in .claude/rules/database.md ("pg-real
  * tests: any PR touching a trigger/RPC/RLS/DEFERRABLE must include or extend
- * a *.pg.test.ts") — previously instruction-only, which means it got skipped.
+ * a *.pg.test.ts"): previously instruction-only, which means it got skipped.
  *
  * Escape hatch: a migration may declare, in a SQL comment, either
  *   -- pg-test: covered-by tests/pg/<file>.pg.test.ts
  *   -- pg-test: skip (<reason>)
- * Both are visible in review and greppable later. Use them sparingly —
+ * Both are visible in review and greppable later. Use them sparingly:
  * "covered-by" when an existing test already exercises the changed object,
  * "skip" when the change is genuinely untestable (e.g. a NOTIFY-only fixup).
  *
- * Scope: the gate is PR-level, not per-migration — ANY *.pg.test.ts change
+ * Scope: the gate is PR-level, not per-migration: ANY *.pg.test.ts change
  * satisfies it. With multiple risky migrations in one PR, reviewers must
  * still confirm each one is actually covered (or carries an escape hatch);
  * mapping tests to migrations automatically would be guesswork.
  *
  * Usage: node scripts/check-pg-test-coverage.mjs
- *   PG_GATE_BASE — git ref to diff against (default: origin/main)
+ *   PG_GATE_BASE: git ref to diff against (default: origin/main)
  */
 import { execFileSync } from 'node:child_process'
 import { existsSync, readFileSync } from 'node:fs'
@@ -32,7 +32,7 @@ let changed
 try {
   // Three-dot diff: changes on the PR side since the merge-base with `base`.
   // --diff-filter=ACMR skips deletions (a deleted migration has no content to
-  // scan). execFileSync with an argv array — no shell, so a hostile base-ref
+  // scan). execFileSync with an argv array: no shell, so a hostile base-ref
   // string can't inject (git just rejects an invalid rev via the catch below).
   changed = execFileSync('git', ['diff', '--name-only', '--diff-filter=ACMR', `${base}...HEAD`], {
     encoding: 'utf8',
@@ -100,7 +100,7 @@ for (const { file, kinds } of flagged) {
 }
 console.error(`
 The repo rule (.claude/rules/database.md) requires real-Postgres coverage for
-these objects — mocked Supabase tests cannot exercise them.
+these objects: mocked Supabase tests cannot exercise them.
 
 Fix one of:
   1. Add or extend a *.pg.test.ts covering the changed trigger/RPC/policy