[AI] Add beaconTimeline to Metrics GraphQL Query

[KCarretto]

This PR adds a beaconTimeline field to the metrics GraphQL query to provide a timeline of beacon check-in statistics.

Changes:

• Added beaconTimeline field and BeaconTimelineBucket type to tavern/internal/graphql/schema/metrics.graphql.
• Configured the new field to generate a resolver stub in tavern/internal/graphql/gqlgen.yml.
• Re-generated the gqlgen and ent code.
• Restored inadvertently downgraded builderpb, c2pb, epb, and portalpb protobuf files modified by go generate.
• Implemented the BeaconTimeline resolver in tavern/internal/graphql/metrics.resolvers.go, referencing the existing QuestTimelineChart resolver to handle time range, granularity bucketing, and where filtering using the BeaconHistory ent.
• All backend GraphQL tests continue to pass.

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PR created automatically by Jules for task 16155986931105137112 started by @KCarretto

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[github-actions]

Summary

Tests 📝	Passed ✅	Failed ❌	Skipped ⏭️	Other ❓	Flaky 🍂	Duration ⏱️
208	208	0	0	0	0	1ms

Previous Results

Build 🏗️	Result 🧪	Tests 📝	Passed ✅	Failed ❌	Skipped ⏭️	Other ❓	Flaky 🍂	Duration ⏱️
#1943	✅	208	208	0	0	0	0	not captured

Insights

Average Tests per Run	Total Flaky Tests	Total Failed	Slowest Test (p95)
208	0	0	733ms

Test Changes

0 test added, 0 removed

Slowest Tests

Test 📝	Results 📊	Duration (avg) ⏱️	Duration (p95) ⏱️
src/context/FilterContext/tests/FilterControls.test.tsx: FilterControls > Filter lock/unlock toggle > should toggle isLocked when lock button is clicked	1	733ms	733ms
src/context/FilterContext/tests/FilterControls.test.tsx: FilterControls > Filter component interactions > should preserve filter values when toggling lock state	1	718ms	718ms
src/context/FilterContext/tests/FilterControls.test.tsx: FilterControls > Filter lock/unlock toggle > should disable filter components when isLocked is true	1	458ms	458ms
src/components/create-shell-button/CreateShellButtonWindowOpen.test.tsx: CreateShellButton opens new tab on click	1	445ms	445ms
src/context/FilterContext/tests/FilterControls.test.tsx: FilterControls > Filter label calculation > should count text search filters correctly	1	410ms	410ms
src/context/FilterContext/tests/FilterControls.test.tsx: FilterControls > Filter component interactions > should update filter state when inputs change	1	341ms	341ms
src/context/FilterContext/tests/FilterControls.test.tsx: FilterControls > Filter label calculation > should count multiple active filters correctly	1	303ms	303ms
src/context/SortContext/tests/SortingControls.test.tsx: SortingControls > Updating sort settings > should update sort field when field dropdown changes	1	289ms	289ms
src/components/tavern-base-ui/table/tests/TablePagination.test.tsx: TablePagination > Navigation callbacks > should call refetchTable with startCursor on Previous click	1	241ms	241ms
src/components/tavern-base-ui/table/tests/Table.test.tsx: Table > Column sorting > should set column width from getSize()	1	210ms	210ms

_{🎉 No failed tests in this run. | 🍂 No flaky tests in this run.}

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