[FEATURE] add alert manager plugin

[jgbernalp]

Description

This PR adds the alert manager plugin:

• Alerts table with hierarchical grouping
• Silence table with action to expire silences
• Alerts explore with action to silence alerts (create silence)
• Silence explore with option to create silences

Part 3 of perses/perses#3645

needs the following PRs: ( CI will fail until these are merged and dependencies are updated )

• [FEATURE] add alerts and silences data type definitions for alert manager plugin spec#21
• [FEATURE] add alert manager query types shared#127
• [FEATURE] add alert and silence query kinds perses#4047 (chicken and egg problem, maybe the query kinds should be part of the spec) cc @Nexucis WDYT?

Screenshots

Screen.Recording.2026-05-04.at.11.26.59.mov

Checklist

• Pull request has a descriptive title and context useful to a reviewer.
• Pull request title follows the [<catalog_entry>] <commit message> naming convention using one of the
  following catalog_entry values: FEATURE, ENHANCEMENT, BUGFIX, BREAKINGCHANGE, DOC,IGNORE.
• All commits have DCO signoffs.

UI Changes

• Changes that impact the UI include screenshots and/or screencasts of the relevant changes.
• Code follows the UI guidelines.

Testing locally

• Pull all the repo PRs locally

# link spec with shared plugin-system
cd <path to perses spec in #21>/ts
npm install
npm run build
cd <path to perses shared in #127>/plugin-system
npm install <relative path to perses spec in #21 e.g. "../../spec/ts">

# link shared with perses
cd <path to perses shared in #127>
npm install
npm run build
./scripts/link-with-perses/link-with-perses.sh --perses

# start perses backend
cd <path to perses in #21>
make build-cli
./scripts/api_backend_dev.sh --e2e

# in a 2nd terminal, start the app in shared mode
cd <path to perses in #21>/ui/app
npm run start:shared

# in a 3rd terminal, start the plugin
cd <path to perses plugins in #647>
<path to perses in #21>/bin/percli plugin start alertmanager

# in a 4th terminal, start the test alert manager and prometheus
cd <path to perses in #21>
podman compose --file dev/docker-compose.yaml --profile prometheus --profile avalanche --profile alertmanager up

And that is all 😅 , we need to script this away... I'll extend the link script