feat(ui): add a Fleet tab to the Stage drawer listing governed Targets

[jsbroks]

Builds on #7183, which added the round progress bar and is now on main.

Summary

A target-aware Stage's drawer had no view of the Targets it governs. The Promotions tab shows its PromotionRequests; nothing listed the Targets themselves with where each stands. This adds a Fleet tab, first in order and the initial tab for target-aware Stages, and the Target endpoints it reads from.

API

Cherry-picked from #7138: GET /v1beta1/projects/{project}/targets and GET .../targets/{target}, following the PromotionRequest endpoints (list-then-watch with resourceVersion seeding, sorted by name).

• labelSelector is applied by the Kubernetes API server, for the list and the watch.
• stage returns only the Targets that Stage governs. A Stage's selectors are a union, which no single label selector expresses, so this filter is evaluated in-process against each Target and each watch event. A classic Stage yields an empty list; a missing Stage is a 404; a malformed selector is a 400.
• Selector parsing and the any-selector-matches test move into pkg/api (TargetSelectorsForStage, AnySelectorMatches); ListTargetsForStage parses through the former, so the controller and the API server share one definition of governance.
• swagger.json and the Go and TypeScript clients are regenerated, now including the Target status types from feat(api): record per-Stage current Freight, health checks, and health on Target status #7174. The user cluster roles already grant read on Targets.

Fleet tab

One row per Target the Stage governs, from the stage filter above:

• Target with its labels.
• Freight the Target is running for this Stage, from Target.status.stages[<stage>].currentFreight (feat(api): record per-Stage current Freight, health checks, and health on Target status #7174), one link per origin. A Target whose collection differs from the Stage's current one is marked behind. Until a Promotion has succeeded, the column shows what the round is promoting.
• Health from status.stages[<stage>].health, with the shared health icon.
• Promotion phase of the child Promotion in the Stage's latest round, linking to it. A Target the round did not name reads "not in latest round"; a round that ended before creating a child shows the round's phase and its Ready message.
• When the round finished.

Rows with trouble sort first. Above them, a card in the style of the Requested Freight cards summarizes the round: its Freight, the PromotionRequest's name, phase, finish time, how many Targets succeeded, one chip per phase present, and the progress bar from #7183 as the card's footer. Card and bar are drawn from the rows' own phases rather than the request's summary, so the card and the table cannot disagree.

The table filters from its column headers, as the UI's other filterable tables do: Target by name or label from a text box, Promotion by phase, and Health by health state, each listing only the values present with counts. Targets stay live through a seeded watch scoped to the Stage. The round comes from a new useCurrentRound hook that resolves the request the Stage is promoting through (current, else last, else newest) from the same PromotionRequest list the Promotions tab shows, sharing its fetch and watch.

Classic Stages do not show the tab and open on Promotions as before. Once a user picks a tab, that choice sticks for the drawer's lifetime.

When a round cannot fan out

The Promotions tab used to warn on its own when the Stage's latest request could not progress, quoting the Ready message. That explanation now sits above the tabs, so the Fleet and Promotions tabs both read under it, and it is worded for the person reading it. When the reconciler reports that fan-out is not available in the installation, the alert says so in plain language with a sentence on what it means for the Stage. Any other reason passes through under "Promotion to this Stage cannot progress". While a round is blocked the Fleet tab shows no round card and no phase chips; its rows read "Not attempted" in grey, and the Health and When columns, which have nothing to say, drop out.

A round that did fan out and then had children fail is not blocked, even though the controller also sets Ready to False for it. roundBlock yields nothing for a request that recorded any Target or summary, so the alert is reserved for rounds that never started and a partially failed round keeps its bar and rows.

Verified

• Go: go test -race on pkg/server and pkg/api, golangci-lint clean.
• UI: pnpm typecheck, pnpm lint, pnpm vitest run (34 files, 407 tests). fleet-utils.test.ts covers row construction, phase fallback, Freight and health from Target status, the behind marker, sort order, the bar's summary, and the Target text match; promotion-request.test.ts covers roundBlock.
• Live against a kind cluster with target-aware Stages, a partially failed round, and Target status seeded for two Targets. Captured the tab on three small Stages, a 40-Target Stage with three failures, the same Stage mid-round with all children pending, a Stage whose request carried the status this repository's reconciler writes, and confirmed a classic Stage is unchanged. Screenshots are in the first comment.

Not in this PR

Deep-linkable tabs, a Targets page, and the bar on other surfaces.

Checklist

Eligibility

• Linked to an existing issue with no blocking labels.
• Changes documentation only.
• Changes ten lines or fewer.

Quality

• Adds or updates corresponding tests.
• Adds or updates corresponding documentation.

AI Use Disclosure

This PR was written:

• By a human without AI assistance.
• By a human with AI assistance. A human has reviewed every line prior to opening the PR.
• By an AI with human supervision. A human has reviewed every line prior to opening the PR.
• Entirely by an AI. No human has reviewed this prior to opening the PR.

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[codecov]

Codecov Report

❌ Patch coverage is 63.84615% with 47 lines in your changes missing coverage. Please review.
✅ Project coverage is 64.96%. Comparing base (260e519) to head (6ea133b).

Files with missing lines	Patch %	Lines
pkg/server/list_targets.go	51.04%	47 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7200      +/-   ##
==========================================
- Coverage   64.97%   64.96%   -0.01%     
==========================================
  Files         511      513       +2     
  Lines       38419    38541     +122     
==========================================
+ Hits        24964    25040      +76     
- Misses      13455    13501      +46     

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[rpelczar]

This triggers a watch on Promotion Requests. We call this hook here, and in the parent component.
Let's pass round param instead of initializing it a second time. I think we can get rid of the stage param.