add dolibarr-thirdparty-completeness and dolibarr-tva-deductible

V4 bundle — two more sibling skills, both read-only, both depending
on the dolibarr base skill.

dolibarr-thirdparty-completeness:
- audit-thirdparty.sh <socid>: country-aware completeness audit for
  any thirdparty (FR: SIREN + SIRET + tva_intra; EU non-FR: tva_intra;
  extra-EU: national tax id). Generalizes the V1 KM-hardcoded script.
- audit-all-thirdparties.sh: loops over /thirdparties and surfaces a
  compact table of gaps. --clients-only / --suppliers-only flags.
- Live baseline finds 5/10 thirdparties with mandatory gaps:
  KissMetrics (US tax id), Wise Europe SA (BE tva_intra), Medialex
  (FR SIRET + tva_intra), Qonto (SIRET), Infogreffe (SIRET).

dolibarr-tva-deductible:
- deductible-by-month.sh: TVA déductible aggregated per period × rate.
- deductible-line-detail.sh: per supplier-invoice line with country-
  based CA3 bucket assignment (ligne 20 for 20 % FR, ligne 19 for
  reduced rates, ligne 17+24 for intra-UE autoliquidation).
- Live baseline: 223.22 € total TVA déductible across 13 lines.
  Wise Europe SA correctly identified as intra-UE autoliquidation;
  La Poste correctly identified as FR exempt (timbres).
- Mirrors dolibarr-tva-reconciliation on the supplier side. Together
  they give the two numbers a CA3 monthly declaration needs.

Also extends dolibarr/SKILL.md endpoint catalogue with /supplierinvoices
(noting the 403 on the /lines sub-endpoint — inline lines on the detail
endpoint make this a non-issue). dolibarr/README.md gains two new
permission checkboxes for Factures fournisseurs.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.claude/skills/dolibarr-thirdparty-completeness/examples/audit-thirdparty-1.txt

@@ -0,0 +1,16 @@
+================================================================================
+ Thirdparty 1 — KissMetrics   [client, country=US]
+================================================================================
+  [OK] name                   = 'KissMetrics'
+  [OK] address                = '2850 34th Street North, 307'
+  [OK] zip                    = '33713'
+  [OK] town                   = 'St. Petersburg'
+  [OK] country_code           = 'US'
+  [XX] idprof1 (tax id / EIN) = ''
+  [--] idprof2                = ''   (optional)
+  [OK] email                  = 'evan@kissmetrics.io'   (optional)
+  [--] phone                  = None   (optional)
+  [--] url                    = None   (optional)
+  [--] iban                   = (not set)   (optional)
+
+  6 pass, 1 mandatory fail(s), 3 optional unset