Refine opportunity and applications workspaces

[JoseMelNet]

• Refines Inbox / Vacancies as an opportunity decision workspace.
• Refines Applications / Seguimiento as an operational follow-up workspace.
• Adds compact Applications header and filters.
• Replaces Applications table with grouped follow-up rail.
• Fixes Applications HTMX selection and public URL behavior.
• Adds sticky detail panel with internal scroll.
• Shows original vacancy analysis as contextual disclosure.
• Adds conservative follow-up signals.
• Reduces detail panel microcopy and hides empty contact/notes sections.
• Preserves q/state/page/page_size/selected across interactions.
• Keeps SQL, OpenAI, Profile, and persistence unchanged.

Validations:

• unittest discover: OK
• ruff: OK
• compileall: OK
• manual smoke: OK

Known non-blocking note:

• If selected does not belong to the active filter, the view falls back to a visible item correctly; the URL may still contain the originally requested selected value.