feat: implement multi-user access and invite flows (#3784)

## Thinking Path

> - Paperclip is the control plane for autonomous AI companies.
> - V1 needs to stay local-first while also supporting shared,
authenticated deployments.
> - Human operators need real identities, company membership, invite
flows, profile surfaces, and company-scoped access controls.
> - Agents and operators also need the existing issue, inbox, workspace,
approval, and plugin flows to keep working under those authenticated
boundaries.
> - This branch accumulated the multi-user implementation, follow-up QA
fixes, workspace/runtime refinements, invite UX improvements,
release-branch conflict resolution, and review hardening.
> - This pull request consolidates that branch onto the current `master`
branch as a single reviewable PR.
> - The benefit is a complete multi-user implementation path with tests
and docs carried forward without dropping existing branch work.

## What Changed

- Added authenticated human-user access surfaces: auth/session routes,
company user directory, profile settings, company access/member
management, join requests, and invite management.
- Added invite creation, invite landing, onboarding, logo/branding,
invite grants, deduped join requests, and authenticated multi-user E2E
coverage.
- Tightened company-scoped and instance-admin authorization across
board, plugin, adapter, access, issue, and workspace routes.
- Added profile-image URL validation hardening, avatar preservation on
name-only profile updates, and join-request uniqueness migration cleanup
for pending human requests.
- Added an atomic member role/status/grants update path so Company
Access saves no longer leave partially updated permissions.
- Improved issue chat, inbox, assignee identity rendering,
sidebar/account/company navigation, workspace routing, and execution
workspace reuse behavior for multi-user operation.
- Added and updated server/UI tests covering auth, invites, membership,
issue workspace inheritance, plugin authz, inbox/chat behavior, and
multi-user flows.
- Merged current `public-gh/master` into this branch, resolved all
conflicts, and verified no `pnpm-lock.yaml` change is included in this
PR diff.

## Verification

- `pnpm exec vitest run server/src/__tests__/issues-service.test.ts
ui/src/components/IssueChatThread.test.tsx ui/src/pages/Inbox.test.tsx`
- `pnpm run preflight:workspace-links && pnpm exec vitest run
server/src/__tests__/plugin-routes-authz.test.ts`
- `pnpm exec vitest run server/src/__tests__/plugin-routes-authz.test.ts
server/src/__tests__/workspace-runtime-service-authz.test.ts
server/src/__tests__/access-validators.test.ts`
- `pnpm exec vitest run
server/src/__tests__/authz-company-access.test.ts
server/src/__tests__/routines-routes.test.ts
server/src/__tests__/sidebar-preferences-routes.test.ts
server/src/__tests__/approval-routes-idempotency.test.ts
server/src/__tests__/openclaw-invite-prompt-route.test.ts
server/src/__tests__/agent-cross-tenant-authz-routes.test.ts
server/src/__tests__/routines-e2e.test.ts`
- `pnpm exec vitest run server/src/__tests__/auth-routes.test.ts
ui/src/pages/CompanyAccess.test.tsx`
- `pnpm --filter @paperclipai/shared typecheck && pnpm --filter
@paperclipai/db typecheck && pnpm --filter @paperclipai/server
typecheck`
- `pnpm --filter @paperclipai/shared typecheck && pnpm --filter
@paperclipai/server typecheck`
- `pnpm --filter @paperclipai/ui typecheck`
- `pnpm db:generate`
- `npx playwright test --config tests/e2e/playwright.config.ts --list`
- Confirmed branch has no uncommitted changes and is `0` commits behind
`public-gh/master` before PR creation.
- Confirmed no `pnpm-lock.yaml` change is staged or present in the PR
diff.

## Risks

- High review surface area: this PR contains the accumulated multi-user
branch plus follow-up fixes, so reviewers should focus especially on
company-boundary enforcement and authenticated-vs-local deployment
behavior.
- UI behavior changed across invites, inbox, issue chat, access
settings, and sidebar navigation; no browser screenshots are included in
this branch-consolidation PR.
- Plugin install, upgrade, and lifecycle/config mutations now require
instance-admin access, which is intentional but may change expectations
for non-admin board users.
- A join-request dedupe migration rejects duplicate pending human
requests before creating unique indexes; deployments with unusual
historical duplicates should review the migration behavior.
- Company member role/status/grant saves now use a new combined
endpoint; older separate endpoints remain for compatibility.
- Full production build was not run locally in this heartbeat; CI should
cover the full matrix.

## Model Used

- OpenAI Codex coding agent, GPT-5-based model, CLI/tool-use
environment. Exact deployed model identifier and context window were not
exposed by the runtime.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] If this change affects the UI, I have included before/after
screenshots
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] I will address all Greptile and reviewer comments before
requesting merge

Note on screenshots: this is a branch-consolidation PR for an
already-developed multi-user branch, and no browser screenshots were
captured during this heartbeat.

---------

Co-authored-by: dotta <dotta@example.com>
Co-authored-by: Paperclip <noreply@paperclip.ing>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

packages/shared/src/project-mentions.ts

@@ -1,5 +1,6 @@
 export const PROJECT_MENTION_SCHEME = "project://";
 export const AGENT_MENTION_SCHEME = "agent://";
+export const USER_MENTION_SCHEME = "user://";
 export const SKILL_MENTION_SCHEME = "skill://";
 
 const HEX_COLOR_RE = /^[0-9a-f]{6}$/i;
@@ -8,6 +9,7 @@ const HEX_COLOR_WITH_HASH_RE = /^#[0-9a-f]{6}$/i;
 const HEX_COLOR_SHORT_WITH_HASH_RE = /^#[0-9a-f]{3}$/i;
 const PROJECT_MENTION_LINK_RE = /\[[^\]]*]\((project:\/\/[^)\s]+)\)/gi;
 const AGENT_MENTION_LINK_RE = /\[[^\]]*]\((agent:\/\/[^)\s]+)\)/gi;
+const USER_MENTION_LINK_RE = /\[[^\]]*]\((user:\/\/[^)\s]+)\)/gi;
 const SKILL_MENTION_LINK_RE = /\[[^\]]*]\((skill:\/\/[^)\s]+)\)/gi;
 const AGENT_ICON_NAME_RE = /^[a-z0-9-]+$/i;
 const SKILL_SLUG_RE = /^[a-z0-9][a-z0-9-]*$/i;
@@ -22,6 +24,10 @@ export interface ParsedAgentMention {
   icon: string | null;
 }
 
+export interface ParsedUserMention {
+  userId: string;
+}
+
 export interface ParsedSkillMention {
   skillId: string;
   slug: string | null;
@@ -111,6 +117,28 @@ export function parseAgentMentionHref(href: string): ParsedAgentMention | null {
   };
 }
 
+export function buildUserMentionHref(userId: string): string {
+  return `${USER_MENTION_SCHEME}${userId.trim()}`;
+}
+
+export function parseUserMentionHref(href: string): ParsedUserMention | null {
+  if (!href.startsWith(USER_MENTION_SCHEME)) return null;
+
+  let url: URL;
+  try {
+    url = new URL(href);
+  } catch {
+    return null;
+  }
+
+  if (url.protocol !== "user:") return null;
+
+  const userId = `${url.hostname}${url.pathname}`.replace(/^\/+/, "").trim();
+  if (!userId) return null;
+
+  return { userId };
+}
+
 export function buildSkillMentionHref(skillId: string, slug?: string | null): string {
   const trimmedSkillId = skillId.trim();
   const normalizedSlug = normalizeSkillSlug(slug ?? null);
@@ -165,6 +193,18 @@ export function extractAgentMentionIds(markdown: string): string[] {
   return [...ids];
 }
 
+export function extractUserMentionIds(markdown: string): string[] {
+  if (!markdown) return [];
+  const ids = new Set<string>();
+  const re = new RegExp(USER_MENTION_LINK_RE);
+  let match: RegExpExecArray | null;
+  while ((match = re.exec(markdown)) !== null) {
+    const parsed = parseUserMentionHref(match[1]);
+    if (parsed) ids.add(parsed.userId);
+  }
+  return [...ids];
+}
+
 export function extractSkillMentionIds(markdown: string): string[] {
   if (!markdown) return [];
   const ids = new Set<string>();