Add /tldr: a private overview of what you missed in a channel

/tldr [since] summarizes the messages in the channel it is run in that the
caller has not been summarized yet, using a small local model on Ollama, and
replies ephemerally. The answer streams into the reply as it is written.

- Per-user, per-channel cursor (tldr_cursors) so each run picks up where the
  last left off; `since:` (e.g. 6h, 2d, max 7d) peeks without moving it.
  First use covers the last 24h, and a stale cursor never reaches back more
  than 7 days.
- Only summarizes channels both the caller and the bot can read.
- The transcript drops bots, system messages, reactions and filler, turns
  links, GIFs, images and files into short tags ([link: site], [image],
  [file: name], preview titles), marks replies, and writes a date marker
  where the chat paused for 3h or more so the model can keep topics apart.
- The prompt asks for one bullet per conversation, oldest first, with a
  worked example; it was tuned against a synthetic chat and a real export
  with qwen3:4b-instruct-2507 (the default model).
- One model call at a time across the bot, one /tldr per user.
- docker-compose: Ollama service (CPU only, 8g memory cap: 6g killed the
  runner mid-request), model pull on startup.

Needs the tldr_cursors migration (velox-dashboard-api 000016).

Co-Authored-By: Claude Opus 5.5 <[email protected]>

internal/commands/commands.go

@@ -12,6 +12,7 @@ import (
 	"velox-bot/internal/commands/projects"
 	"velox-bot/internal/commands/schedule"
 	"velox-bot/internal/commands/timezone"
+	"velox-bot/internal/commands/tldr"
 	"velox-bot/internal/music"
 
 	"github.com/bwmarrin/discordgo"
@@ -37,6 +38,7 @@ var AllCommands = []*discordgo.ApplicationCommand{
 	meeting.Meeting,
 	moderation.Moderation,
 	timezone.Timezone,
+	tldr.Tldr,
 	schedule.Schedule,
 	projects.Projects,
 	config.Config,
@@ -58,6 +60,7 @@ var handlers = map[string]func(s *discordgo.Session, i *discordgo.InteractionCre
 	"meeting":        meeting.MeetingHandler,
 	"moderation":     moderation.ModerationHandler,
 	"timezone":       timezone.TimezoneHandler,
+	"tldr":           tldr.TldrHandler,
 	"schedule":       schedule.ScheduleHandler,
 	"projects":       projects.ProjectsHandler,
 	"play":           cmdmusic.PlayHandler,