refactor(admin): unify confirm dialog — pure hx-confirm + form[method=dialog]

Eliminate `confirmAction()` and the duplicate `cloneNode` hack entirely.
One code path: everything goes through `showConfirm()` called by the
`htmx:confirm` interceptor.

Dialog HTML:
- `<form method="dialog">` for native close semantics; button `value`
  becomes `dialog.returnValue` — no manual event listener reassignment.

JS:
- `showConfirm(message)` — Promise-based, listens for `close` once.
- `htmx:confirm` handler calls `showConfirm()` and calls `issueRequest`
  if confirmed. Replaces both the old HTMX handler and `confirmAction()`.

Templates (Padelnomics, 14 files):
- All `onclick=confirmAction(...)` and `onclick=confirm()` removed.
- Form-submit buttons: added `hx-boost="true"` to form + `hx-confirm`
  on the submit button.
- Pure HTMX buttons (pipeline_transform, pipeline_overview): `hx-confirm`
  replaces `onclick=if(!confirm(...))return false;`.

Pipeline routes (pipeline_trigger_extract, pipeline_trigger_transform):
- `is_htmx` now excludes `HX-Boosted: true` requests — boosted form
  POSTs get the normal redirect instead of the inline partial.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -7,6 +7,12 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 ## [Unreleased]
 
 ### Changed
+- **Unified confirm dialog — pure HTMX `hx-confirm` + `<form method="dialog">`** — eliminated the `confirmAction()` JS function and the duplicate `cloneNode` hack. All confirmation prompts now go through a single `showConfirm()` Promise-based function called by the `htmx:confirm` interceptor. The dialog HTML uses `<form method="dialog">` for native close semantics (`returnValue` is `"ok"` or `"cancel"`), removing the need to clone and replace buttons on every invocation. All 12 Padelnomics call sites converted from `onclick=confirmAction(...)` to `hx-boost="true"` + `hx-confirm="..."` on the submit button. Pipeline trigger endpoints updated to treat `HX-Boosted: true` requests as non-HTMX (returning a redirect rather than an inline partial) so boosted form submissions flow through the normal redirect cycle. Same changes applied to BeanFlows and the quart-saas-boilerplate template.
+  - `web/src/padelnomics/admin/templates/admin/base_admin.html`: replaced dialog `<div>` with `<form method="dialog">`, replaced `confirmAction()` + inline `htmx:confirm` handler with unified `showConfirm()` + single `htmx:confirm` listener
+  - `web/src/padelnomics/admin/pipeline_routes.py`: `pipeline_trigger_extract` and `pipeline_trigger_transform` now exclude `HX-Boosted: true` from the HTMX partial path
+  - 12 templates updated: `pipeline.html`, `partials/pipeline_extractions.html`, `affiliate_form.html`, `affiliate_program_form.html`, `partials/affiliate_program_results.html`, `partials/affiliate_row.html`, `generate_form.html`, `articles.html`, `audience_contacts.html`, `template_detail.html`, `partials/scenario_results.html`
+  - Same changes mirrored to BeanFlows and quart-saas-boilerplate template
+
 - **Per-proxy dead tracking in tiered cycler** — `make_tiered_cycler` now accepts a `proxy_failure_limit` parameter (default 3). Individual proxies that hit the limit are marked dead and permanently skipped by `next_proxy()`. If all proxies in the active tier are dead, `next_proxy()` auto-escalates to the next tier without needing the tier-level threshold. `record_failure(proxy_url)` and `record_success(proxy_url)` accept an optional `proxy_url` argument for per-proxy tracking; callers without `proxy_url` are fully backward-compatible. New `dead_proxy_count()` callable exposed for monitoring.
   - `extract/padelnomics_extract/src/padelnomics_extract/proxy.py`: added per-proxy state (`proxy_failure_counts`, `dead_proxies`), updated `next_proxy`/`record_failure`/`record_success`, added `dead_proxy_count`
   - `extract/padelnomics_extract/src/padelnomics_extract/playtomic_tenants.py`: `_fetch_page_via_cycler` passes `proxy_url` to `record_success`/`record_failure`