feat(farm_onboarding): systray bell + post_init hook autostart

[dnplkndll]

What changed

First slice of the UX-refinement plan (Step 1 of 5). The onboarding wizard now surfaces itself instead of waiting for users to find the menu.

farm_pack

• New post_init_hook (farm_pack/hooks.py) seeds one farm.onboarding.session per (internal farm user, company) on install. Existing installs upgrade and get the bell immediately; new users get a session lazily. Idempotent — re-runs do not duplicate. Portal users (share=True) and tooling accounts are excluded.
• Manifest gains the hook reference + version bump 19.0.1.0.0 → 19.0.1.1.0.
• New farm_pack/tests/test_post_init_hook.py covers: idempotency, fresh-user seeding, portal-user exclusion, multi-company users get one session per company, and users in both portal + farm groups are still excluded.

farm_onboarding

• First OWL component in the pack: FarmOnboardingSystray (static/src/js/onboarding_systray.esm.js + static/src/xml/onboarding_systray.xml). Leaf icon + red badge dot appears in the navbar when the current user has a pending session. Click → opens the wizard via the existing action_open_for_current_user server action.
• Component is invisible (t-if) when no session is pending, so non-farm users see nothing. The count_pending_for_current_user RPC is wrapped in try/catch with a state.pending=0 fallback so users without farm_base.group_farm_user don't generate AccessError console spam on every page load.
• New count_pending_for_current_user @api.model RPC kept separate from get_or_create_for_current_user so the bell's mount path is read-only — it must not create session rows on page load.
• assets.web.assets_backend block added for the JS + template. First JS assets the pack ships.
• Manifest version bump 19.0.1.0.0 → 19.0.1.1.0.

Docs

• farm_onboarding/readme/DESCRIPTION.md + USAGE.md updated to describe the navbar bell as the primary discovery surface.
• farm_pack/readme/DESCRIPTION.md documents the post_init_hook seeding behavior.
• First two newsfragments in the pack: farm_onboarding/readme/newsfragments/+systray_bell.feature.md and farm_pack/readme/newsfragments/+post_init_seed.feature.md.
• README.rst + static/description/index.html regenerated by oca-gen-addon-readme.

Why the .esm.js suffix

The repo's eslint.config.cjs defaults sourceType: script and only treats files matching **/*.esm.js or **/*test.js as ES modules. Using .esm.js is the OCA-standard escape hatch for OWL components in this codebase. Odoo's module loader accepts both naming conventions.

Commits

Four reviewable commits land this PR:

1. feat(farm_onboarding): systray bell + post_init hook autostart — the feature itself.
2. fix(farm_onboarding): handle systray RPC failure gracefully — try/catch around the mount-time RPC so users outside farm_base.group_farm_user don't see console errors.
3. test(farm_onboarding,farm_pack): cover multi-company + portal-overlap edges — two new test cases (multi-company seeding, hybrid portal+farm user excluded) + datetime cleanup.
4. docs(farm_onboarding,farm_pack): describe systray bell + post_init_hook — README fragments, newsfragments, docstring tighten, log-line clarity.

Tests

• test_count_pending_for_current_user — verifies 0 when nothing pending, increments on creation, returns to 0 on skip/done.
• test_post_init_hook.py:
  • test_hook_is_idempotent — re-run on installed db does not duplicate.
  • test_hook_creates_session_for_new_farm_user — fresh user gets seeded.
  • test_hook_skips_portal_users — portal users excluded.
  • test_hook_skips_user_holding_both_portal_and_farm_groups — hybrid users still excluded (share=True wins).
  • test_hook_seeds_one_session_per_company_for_multi_company_user — pins multi-company shape so future refactors don't silently regress.

Test plan

• CI green on 19.0
• Smoke install on local doodba (blocked on task #42: workspace odoo container exited OOM in prior session; bring-up still pending). Once that's resolved: install farm_pack against a db with an existing admin user; log in; see the leaf-icon + red dot in the navbar; click; the wizard form opens; complete or skip; reload; bell is gone.

Screenshots

Deferred — the local doodba workspace's odoo container is currently down (industry-packs-odoo-1 exited 137 / OOM, ~30 hours ago). Screenshots will be attached as a PR comment once the smoke-install workstream (task #42) brings the workspace back up. The behavior is fully covered by the server-side tests in the meantime.

What's NOT in this PR (per the plan)

• Visual design — the bell uses a plain Font Awesome leaf icon + Bootstrap utility classes. Step 2 of the plan (feat/farm-onboarding-design-pass) is the design pass that styles both the bell and the wizard itself.
• Wizard answers don't yet seed concrete records (Step 3).
• No QBO-import success state (Step 4) or post-onboarding checklist widget (Step 5).