feat(cli): v2 — full API coverage, profiles, --json/--yes, containr up

Rewrite the CLI as a thin client over the authenticated API so agents
and scripts reach every resource the UI does (ROADMAP2 phase A2).

- shared Client with bearer auth, error-envelope decoding, and stable
  exit codes: 0 ok / 1 error / 2 auth / 3 not-found / 4 validation /
  5 unreachable
- named profiles in ~/.containr.yaml (current_profile + profiles.*);
  resolution order --flag > env > profile > localhost default;
  CONTAINR_TOKEN / CONTAINR_API_URL / CONTAINR_PROFILE env support
- --json prints raw API responses; --yes skips confirmations;
  destructive commands refuse non-interactively without it
- auth login verifies the token against /user/profile before saving,
  interactive prompt via term.ReadPassword
- commands for every resource: tokens, projects, services, deploy,
  deployments (logs/rollback), logs --follow (SSE), exec, variables
  (set/unset merge with secret masking preserved), databases
  (backup/restore/download), cron, templates, nodes + agent tokens,
  scaling, ha, security, gateway, admin, notifications
- containr up: git remote + branch → create-or-reuse service → deploy

Verified live: login/status/tokens/projects/services, up creating a
service + deployment, non-TTY confirmation refusal, scope-capped admin
rejection (exit 2), revoke.

Authored By: TDvorak <[email protected]>

app/backend/go.sum

@@ -219,6 +219,8 @@ golang.org/x/sys v0.0.0-20220704084225-05e143d24a9e/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.48.0 h1:bbX/i/6MgT9BVLM9RT1thmxL04yeTAhbEz4SyadbXoo=
 golang.org/x/sys v0.48.0/go.mod h1:hNLxWAXmnKAxqDtdwIYC4bM9oQPEecfsnNMuSxOs3og=
+golang.org/x/term v0.46.0 h1:3+OXuTbaKDgwk8jTi3aSLHRlmWqHEUDUtxnbFigO4YE=
+golang.org/x/term v0.46.0/go.mod h1:+K02xbkittuwc0Am4abfA3Fc+XRGXkvBXNO88NCXPoc=
 golang.org/x/text v0.42.0 h1:JbOZXgfeCPU9gacVtYliJqOhD+zhrEqK4LfdpmlUZqI=
 golang.org/x/text v0.42.0/go.mod h1:ojzP1Z+2QtioaF8DTtO8K5q7JWVVYwZKenzujK0Zd0E=
 golang.org/x/time v0.11.0 h1:/bpjEDfN9tkoN/ryeYHnv5hcMlc8ncjMcM4XBk5NWV0=