[19.0][ADD] spreadsheet_dashboard_subscription_oca: subscription dashboards

[alvaro-domatix]

Ready-to-use spreadsheet dashboards for subscriptions, built on the community spreadsheet_dashboard engine with no Enterprise dependency. Four dashboards are shipped under a dedicated Subscriptions group in the Dashboards app (auto_install wires them up when both spreadsheet_dashboard and subscription_oca are present):

• Subscriptions — monthly/annual recurring revenue, active subscriptions and average MRR, with breakdowns by template, product category, sales team, salesperson, start month and stage.
• Salesperson — recurring revenue and number of subscriptions by salesperson and sales team.
• MRR Evolution — net/new/churned MRR and the cumulated MRR over time (change events derived from start/close dates; mid-life expansion/contraction is not tracked).
• Retention — cohort sizes and recurring revenue per start month, plus a survival curve from start/close dates.

All dashboards expose global filters (salesperson, sales team, customer, template). The MRR/retention figures are produced by two SQL models defined in this module, which read the recurring_monthly field of subscription_oca.

⚠️ Depends on OCA/contract#1451 (compute MRR and ARR), which adds the recurring_monthly field on sale.subscription that the MRR/retention SQL views read. The CI will stay red on the view creation (column sub.recurring_monthly does not exist) until that PR lands in OCA/contract. Originally opened as OCA/contract#1472 and moved here following @popadron's placement review.

[alvaro-domatix]

Note on the failing tests: the MRR/retention SQL views read sale_subscription.recurring_monthly, a field introduced by OCA/contract#1451 (compute MRR and ARR), which is not merged yet. Once that PR lands in OCA/contract, the views will create cleanly and this PR's CI will go green. Pre-commit and runboat already pass; the module itself is complete.

[chrisandrewmann]

@alvaro-domatix thanks for this. However the spreadsheet default branch is still 18.0 as the core spreadsheet_oca and spreadsheet_dashboard_oca are not successfully migrated to 19.0 yet.
There is a PR but it's a long way off being usable. I think we should focus on getting that done first before adding new modules.

[alvaro-domatix]

@chrisandrewmann thanks for the context. I originally opened this as OCA/contract#1472 and moved it here following @popadron's placement review, so I'd like to double-check with you how you'd prefer to proceed.

When I checked the 19.0 dependencies, spreadsheet_dashboard already resolved from the community core (shipped with Odoo itself), so this addon only needed subscription_oca from OCA/contract on top — that's why it didn't look blocked by the spreadsheet_oca/spreadsheet_dashboard_oca migration. The remaining red CI is just OCA/contract#1451 (recurring_monthly field), unrelated to the spreadsheet framework.

Happy to hold this PR, or to close it and re-open OCA/contract#1472 if you'd rather keep this repo dormant until there's a clearer 19.0 policy. Let me know which you prefer and I'll align.

[chrisandrewmann]

@alvaro-domatix thanks. I was hoping to contribute to spreadsheet_oca 19 migration but busy with other projects. I've actually submitted a PR to subscription_oca (OCA/contract#1463) for recurring automated payments which I feel should be high priority.
Although I'm not on the OCA board. I'll leave it to you to decide.