feat: project colors, timeline filters, sidebar fix, GitLooper agent, and misc improvements

- Fix sidebar double-highlight on /vacations/my (Gitea #6): add isNavItemActive() helper
- Add project color picker (schema + API + modal + timeline rendering)
- Add ProjectCombobox/ResourceCombobox to timeline toolbar
- Show PENDING vacations on timeline with dashed/dimmed style
- Add "show demand projects" preference with localStorage persistence
- Add ProjectAssignmentsTable with total hours/cost columns
- Extend vacation API to accept status arrays
- Add GitLooper formal YAML agent configuration
- Extend user admin with permission overrides UI
- Add delete-assignment use case tests
- Add status-styles.ts shared badge constants
- Centralize formatMoney/formatCents in format.ts

Co-Authored-By: claude-flow <ruv@ruv.net>

packages/db/prisma/schema.prisma

@@ -806,6 +806,7 @@ model Project {
   endDate         DateTime       @db.Date
   status          ProjectStatus  @default(DRAFT)
   responsiblePerson String?
+  color             String?           // Hex color for timeline display, e.g. "#3b82f6"
 
   // staffingReqs: StaffingRequirement[]
   staffingReqs    Json           @db.JsonB @default("[]")