feat: allow short video uploads for segment suggestions

[JustSamuel]

Summary

Adds video as a third kind for segment suggestions, alongside photo and voice -- not for chat attachments, per the earlier scope decision.

• Backend: 50MB cap, video/mp4 / video/quicktime / video/webm allow-list, enforced server-side that kind=video is rejected for purpose=chat_attachment (not just omitted from the chat UI).
• SegmentSuggestion.vue: a third "Video" toggle reusing the existing photo file-picker flow (pick an existing clip, not record one live).
• Media tab: a <video> player alongside the existing image/audio branches.

Test plan

• Backend: go build ./... && go vet ./... && go test ./... -race clean
• Frontend: yarn type-check && yarn lint && yarn test clean, 311/311
• Checked live in a browser preview: the card's copy and toggle render correctly under the down/night-hours gating

[github-actions]

Go test coverage

radiogaga/agenda.go:54:		Error				100.0%
radiogaga/agenda.go:64:		NewAgenda			100.0%
radiogaga/agenda.go:83:		Load				95.2%
radiogaga/agenda.go:126:	List				100.0%
radiogaga/agenda.go:143:	Replace				85.7%
radiogaga/agenda.go:190:	validateAgendaEvent		100.0%
radiogaga/agenda.go:226:	sortAgendaEvents		100.0%
radiogaga/agenda.go:239:	startMinutes			100.0%
radiogaga/agenda.go:249:	defaultAgendaEvents		100.0%
radiogaga/audit.go:53:		NewAuditLog			100.0%
radiogaga/audit.go:62:		Load				91.7%
radiogaga/audit.go:85:		List				100.0%
radiogaga/audit.go:102:		Record				94.1%
radiogaga/audit.go:139:		auditLogHandler			100.0%
radiogaga/chat.go:28:		writeMessage			100.0%
radiogaga/chat.go:35:		writeControl			100.0%
radiogaga/chat.go:139:		NewChat				100.0%
radiogaga/chat.go:156:		checkOriginAllowed		100.0%
radiogaga/chat.go:169:		HandleWS			87.7%
radiogaga/chat.go:300:		handleClient			90.0%
radiogaga/chat.go:331:		dispatch			100.0%
radiogaga/chat.go:380:		dispatchTyping			83.3%
radiogaga/chat.go:398:		broadcastTyping			100.0%
radiogaga/chat.go:407:		forwardTypingToUser		100.0%
radiogaga/chat.go:421:		Shutdown			100.0%
radiogaga/chat.go:435:		forwardToRadios			72.7%
radiogaga/chat.go:451:		forwardToOtherRadios		72.7%
radiogaga/chat.go:473:		broadcastPresence		72.7%
radiogaga/chat.go:492:		forwardToUser			64.3%
radiogaga/chat.go:514:		verifyGEWISTokenHandshake	75.0%
radiogaga/chat.go:546:		lidnrValid			100.0%
radiogaga/chat.go:553:		radioKeyValid			100.0%
radiogaga/chat.go:562:		VerifyRadioKey			100.0%
radiogaga/env.go:10:		init				100.0%
radiogaga/env.go:17:		String				66.7%
radiogaga/env.go:29:		StringSlice			100.0%
radiogaga/main.go:59:		normalizePort			100.0%
radiogaga/main.go:81:		healthHandler			100.0%
radiogaga/main.go:87:		tokenHandler			100.0%
radiogaga/main.go:92:		radioHandler			100.0%
radiogaga/main.go:125:		radioKeyValidateHandler		94.1%
radiogaga/main.go:160:		agendaHandler			100.0%
radiogaga/main.go:205:		newMux				67.9%
radiogaga/main.go:249:		newHTTPServer			100.0%
radiogaga/main.go:260:		main				0.0%
radiogaga/media.go:72:		NewMediaStore			100.0%
radiogaga/media.go:79:		Load				91.7%
radiogaga/media.go:102:		List				100.0%
radiogaga/media.go:111:		Get				100.0%
radiogaga/media.go:131:		Add				75.0%
radiogaga/media.go:151:		ReadBytes			92.3%
radiogaga/media.go:176:		Delete				93.3%
radiogaga/media.go:206:		DeleteMany			100.0%
radiogaga/media.go:216:		filePath			100.0%
radiogaga/media.go:238:		sweepExpiredChatAttachments	100.0%
radiogaga/media.go:257:		RunSweep			0.0%
radiogaga/media.go:320:		broadcastMediaEvent		71.4%
radiogaga/media.go:336:		mediaUploadHandler		78.9%
radiogaga/media.go:472:		decodeAndAuthorize		42.9%
radiogaga/media.go:488:		mediaListHandler		92.9%
radiogaga/media.go:516:		mediaDownloadHandler		66.7%
radiogaga/media.go:548:		mediaDeleteHandler		53.8%
radiogaga/media.go:574:		mediaWipeHandler		78.9%
radiogaga/metrics.go:58:	NewMetricsStore			100.0%
radiogaga/metrics.go:68:	Load				91.7%
radiogaga/metrics.go:90:	List				100.0%
radiogaga/metrics.go:104:	Append				88.9%
radiogaga/metrics.go:125:	Run				0.0%
radiogaga/metrics.go:142:	sampleOnce			100.0%
radiogaga/metrics.go:198:	normalizeIcecastBaseURL		100.0%
radiogaga/metrics.go:206:	fetchListenerCount		90.0%
radiogaga/metrics.go:257:	liveStatusHandler		90.0%
radiogaga/metrics.go:295:	metricsHandler			100.0%
radiogaga/metrics.go:321:	writeJSONFile			57.1%
radiogaga/status.go:30:		statusHandler			91.7%
total:				(statements)			81.0%

[github-actions]

Coverage Report for frontend

Status	Category	Percentage	Covered / Total
🔵	Lines	88.35%	1312 / 1485
🔵	Statements	85.91%	1440 / 1676
🔵	Functions	83.3%	454 / 545
🔵	Branches	81.39%	884 / 1086

File Coverage

File	Stmts	Branches	Functions	Lines	Uncovered Lines
Changed Files
frontend/src/components/SegmentSuggestion.vue	70%	63.44%	66.66%	73.19%	107-108, 120-136, 140, 155, 159-160, 165, 169, 193-196, 9-10, 46-55
frontend/src/pages/backoffice/media.vue	63.8%	60.25%	54.76%	69.23%	176, 193, 200, 218-219, 224, 231-236, 249-257, 265, 276, 20-21, 35-48, 97, 113-123
frontend/src/stores/chat.ts	94.44%	94.91%	88.23%	97.46%	110-111, 190, 192, 194

Generated in workflow #112 for commit e38e968 by the Vitest Coverage Report Action