feat(fusion_accounting): add check_odoo_diff.sh for cross-version upgrade ritual

Made-with: Cursor

fusion_accounting/tools/README.md

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+# Fusion Accounting Tooling
+
+## check_odoo_diff.sh
+
+Diff a single Odoo Enterprise accounting module across two pinned snapshots
+in `RePackaged-Odoo/` and produce a categorized change report (markdown).
+
+### Usage
+
+    tools/check_odoo_diff.sh <module> <from_version> <to_version> [<output_md>]
+
+### Example
+
+    # When Odoo 20 ships, get a full report on what changed in account_accountant
+    tools/check_odoo_diff.sh account_accountant v19 v20 > reports/v20_accountant.md
+
+### Classification tags
+
+- `[MIRROR]` — mechanical port required (view XML, OWL component, PDF template, wizard view)
+- `[ABSTRACT]` — verify our adapter still aligns; update if Odoo's public API surface changed
+- `[MANIFEST]` — manifest changes (deps, asset bundles, version, hooks)
+- `[TEST]` — Odoo's tests changed; check if our equivalents need updates
+- `[REVIEW]` — uncategorized; manual review needed
+
+### Snapshot conventions
+
+Snapshots live at `$REPACKAGED_ODOO_ROOT/accounting-<version>/<module>` (default
+root: `/Users/gurpreet/Github/RePackaged-Odoo`). Override the root with the
+`REPACKAGED_ODOO_ROOT` env var.
+
+The current workspace has only the V19 snapshot at
+`/Users/gurpreet/Github/RePackaged-Odoo/accounting/` (unversioned). When
+Odoo 20 ships:
+
+1. Rename the current snapshot: `mv accounting accounting-v19`
+2. Drop the new V20 source at `accounting-v20/`
+3. Run `tools/check_odoo_diff.sh account_accountant v19 v20` per sub-module