Add sidebar Page commands and private subtree duplication

[3mdistal]

Content sidebar rows now offer the same navigation and Page commands through ellipsis, right-click, and keyboard menus. Rename and Move retain the Page identity; Duplicate creates a private copy of the complete supported native Page tree at the root of the same workspace.

The copy receives fresh Page, Block, and Page-property identities, keeps Reference targets, and creates ordinary Files memberships. It rejects unsupported or inaccessible descendants atomically. A caller-scoped receipt makes uncertain-response retries return the same copy. Private organization-space copies are visible in Files only to their owner, with the same filter applied before counts, pagination, and row loading.

The command dialog reads current server-authorized metadata and Move destinations. The read-only side preview follows canonical edits without changing the active Page. Existing pin/delete callbacks remain owned by their existing actions. Database-row duplication also uses independent canonical root positions instead of treating database membership as parentage.

Verification

• 80 tests across seven focused SQL and component suites pass, covering duplicate payload/identity, retries, access denial, property remapping, concurrent root allocation, private Files pagination, viewer commands, cached-read failures, and both sidebar renderers.
• Full Content TypeScript and formatting pass; all 24 new command keys translated across 11 locales.
• Real local owner/viewer UI checks prove matching menus, rename/Move identity and reload, three-level duplication and private access, personal pin isolation, canonical preview synchronization, clipboard contents, and 390px menu/dialog fit.
• Independent mutation and access reviews found no remaining scoped issues after fixes.

Draft limits and review focus

This is a draft for coordinated sidebar integration. The shared Enter/DnD conflict is being addressed separately in the personal-ordering change. Only the in-app browser was available: native new-tab href is correct, but native new-tab/modifier gesture completion could not be observed. Source-denial/reference/unsupported-payload cases have SQL proof rather than separate UI fixtures. Root-position locking matches the existing per-process primitive; cross-process PostgreSQL contention is not established.

Required repository checks are not all green: the catalog guard reports 2,110 local import and catalog/baseline findings; changed-copy inspected zero surfaces locally; the product-impact suite has 9 Windows CLI/workflow fixture failures (21 pass). No guard baselines or bypasses changed. No Capability is promoted to verified, and no merge or deployment is requested.

content_product_impact:
  lane: contract_fulfillment
  features:
    - content.feature.find-your-place-again
    - content.feature.durable-foundations
  capabilities:
    - content.navigation.sidebar
    - content.command.fabric
    - content.object.page
    - content.object.reference
    - content.workspace.view-instance
    - content.object.multi-membership
    - content.source.sync-policy
  record_change: none
  proof:
    - Focused Content action and sidebar tests
    - Content TypeScript check
    - Isolated owner/viewer browser workflows on built source
  rationale: Implements sidebar Page commands while preserving identity, personal navigation, source boundaries, and access; complete Capability verification remains separate.