add bin/arcodange CLI and dolibarr-tva-summary skill

Two changes that go together: now operators can run every read-only
workflow without going through Claude. The skills (SKILL.md files)
remain the source of behaviour documentation and Claude triggers;
bin/arcodange is the human-facing entry point.

bin/arcodange:
- Bash dispatcher at the project root. Subcommands per domain:
  tva {collect, collect-detail, deductible, deductible-detail, summary},
  invoice {list, audit}, thirdparty {audit, audit-all},
  payments {state, timeline, by-month},
  templates {list, inspect},
  snapshot, whoami, ping, curl, help.
- Locates the project root via `git rev-parse` so it works from any
  CWD (including from a worktree).
- Per-subcommand `help` text. Unknown commands exit 2 with a hint.
- Reuses the existing per-skill scripts under .claude/skills/<name>/
  scripts/ via `exec` (zero behaviour drift, full credit to the
  existing tested code).

dolibarr-tva-summary:
- Composes dolibarr-tva-reconciliation (TVA collectée customer-side)
  and dolibarr-tva-deductible (TVA déductible supplier-side) into a
  single CA3-ready monthly summary with per-month net verdict
  (TVA à reverser / crédit de TVA / équilibre) and a cumulative line.
- Live baseline: Arcodange en crédit de TVA de 223.22 € cumulé
  (0 € collectée 259-1° CGI vs 223.22 € déductible).
- Exposed as `arcodange tva summary [--year|--since|--until]`.

Each existing skill's SKILL.md gets a one-line "CLI shortcut" near
the top so the human path is discoverable from any skill page.
The project root README.md gets a CLI section as the primary
operator entry point.

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

.claude/skills/dolibarr/SKILL.md

@@ -16,9 +16,16 @@ The API key for `ai_agent` is **read-only by design**. Never attempt writes from
 
 From the repo root:
 
+```bash
+bin/arcodange whoami | jq -r .login           # → ai_agent
+bin/arcodange ping                            # → {"success":{"code":200,"dolibarr_version":"22.0.4",...}}
+bin/arcodange curl /invoices/12               # raw read-only call
+```
+
+The `bin/arcodange` CLI is the human entry point; under the hood it delegates to the same per-skill scripts. Direct script access still works:
+
 ```bash
 ./.claude/skills/dolibarr/scripts/dol-curl.sh /users/info | jq -r .login
-# → ai_agent
 ```
 
 If you see `ai_agent`, auth works. If not, check `.env` (next section) and `dol-curl.sh`'s error message.
@@ -142,6 +149,7 @@ Not available on this account (intentionally): `/setup/modules` (admin-only), `/
 - Workflow skill for point-in-time state archival: [dolibarr-data-snapshot](../dolibarr-data-snapshot/SKILL.md).
 - Workflow skill for thirdparty completeness audit (any client / supplier): [dolibarr-thirdparty-completeness](../dolibarr-thirdparty-completeness/SKILL.md).
 - Workflow skill for supplier-side TVA déductible (CA3 lignes 19 / 20 / 17+24): [dolibarr-tva-deductible](../dolibarr-tva-deductible/SKILL.md).
+- Workflow skill for composite CA3-ready TVA summary (collectée + déductible + net): [dolibarr-tva-summary](../dolibarr-tva-summary/SKILL.md).
 - Future workflow skills follow the `dolibarr-<topic>` convention. Each one depends on this skill for connection + permissions + endpoint reference; each one keeps its triggers focused on its specific business workflow.
 
 ## Out of scope