## Context
For Database Connections - the PIDs on the overview cards are selectable
such that clicking on them should scroll the browser down to where the
row is.
However, if the selected PID isn't rendered due to the applied filters,
clicking on it will seemingly do nothing. Changes here hence opt to
remove all filters then scroll to the selected PID into view, so that
users can always quickly find which PID the overview card is
referencing.
Also chucked in some refactors to centralize the management of filters,
and functionality of selecting a PID into their own hooks
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Added shared filtering for database activity by state, role,
application, search text, and view.
* Activity filters are now preserved in the URL for easier navigation
and sharing.
* Selecting activity metrics or process IDs now automatically reveals
the relevant activity row.
* Blocker view highlights root activities that are blocking other
queries.
* **Bug Fixes**
* Improved selection behavior when the chosen activity is hidden by
active filters.
* **Tests**
* Added coverage for individual, combined, case-insensitive, and
blocker-specific filtering scenarios.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
## Context
Related to database connections - specifically for cancelling queries or
terminating sessions
PIDs can be re-used, so a more accurate check is to use both PID and
`backend_start` to uniquely identify the session to cancel or terminate
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Bug Fixes**
* Improved query cancellation and session termination reliability by
verifying the active database session before taking action.
* Prevented actions from affecting a different session that reused the
same process ID.
* Added clearer guidance to refresh when a session has changed or is no
longer available.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
## Context
One for Database Connections - allow a user to view the root blocking
queries
Adds an additional filter button here that toggles the view
<img width="738" height="142" alt="image"
src="https://github.com/user-attachments/assets/9fea17ba-c6f6-419d-8847-47dba67fc00a"
/>
When toggled, will render a list of the _root_ blocking queries - these
are queries that are at the end of the blocking chain (or otherwise the
problematic ones causing other queries to be blocked)
<img width="964" height="420" alt="image"
src="https://github.com/user-attachments/assets/5300f523-6abe-49b6-92d0-7e16bbddd291"
/>
Within this view - you can expand the row to view the blocking chain
<img width="950" height="335" alt="image"
src="https://github.com/user-attachments/assets/bb07095a-3841-4db6-8959-ac2bb264ebf6"
/>
## Other changes involved
- Realised that "Top blocker" overview metric card logic is incorrect
- Was previously naively checking the length of the `blocked_by` array,
but it should be consider the nested chain length instead, so this PR
fixes that
<img width="364" height="108" alt="image"
src="https://github.com/user-attachments/assets/89beccef-f6f0-43d1-9dcf-fc35958b09e5"
/>
- Clicking the PID if highlighted on a metric card will not scroll to
the PID if it's already selected. This PR fixes that
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Added a **Root blockers** view to highlight sessions that block
others, with expandable blocking chains revealing related waiting
activity.
* **Bug Fixes**
* Updated blocking metrics to use **transitive** blocker counts and
improved cycle protection and behavior when activity records are
missing.
* The blockers view now consistently affects state/application/role
quantities, and **reset filters** clears the view.
* **Refactor / UI**
* Improved the sessions table with grouped/nested rows, clearer waiting
indicators, and more consistent expand/collapse behavior.
* **Tests**
* Expanded coverage for blocking/waiting chain traversal and branching
scenarios.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
## Context
As per PR title - no functional / visual changes, just some code clean
up / refactor + adding unit tests
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Added database connection metrics covering active, blocked, and
idle-in-transaction queries.
* Enhanced insights for the longest-running query and the top blocker
(most queries blocked), including warning indicators based on duration
thresholds.
* **Bug Fixes**
* Improved consistency and accuracy of database-activity calculations in
the connection overview.
* **Refactor**
* Centralized metric derivation so the UI uses the same computed logic
everywhere.
* **Tests**
* Added metric-calculation tests with controlled time to validate
multiple scenarios and warning behaviors.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
