fix(docs): re-anchor system-context census after activation-gate docblock shift

The activation-gate docblock correction in this branch is one line shorter
than the text it replaced, so both `ec.isSystem` elevation reads moved up
by one line. Row 56's anchors on the system-context census page still
pointed at the old lines, which the census gate reports from both
directions at once: [site-without-a-row] for :138 and :189, and
[anchor-is-not-a-read-site] for the stale :139 and :190.

Pure line rot, repaired by the gate's own `--fix`. Only the two anchor
numbers move; no elevation behaviour text changes.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

Author: hotlong

content/docs/permissions/system-context.mdx

@@ -164,7 +164,7 @@ The largest single consumer — **17 of the 106 sites**.
 | 53 | MCP principal check satisfied | runtime | Get: MCP surface reachable with no user | `domains/mcp.ts:61` |
 | 54 | Package REST route capability gate bypassed | rest | Get: package read/write over REST without `manage_metadata` / `studio.access` / `setup.access` | `package-routes.ts:102` |
 | 55 | Package domain capability gates bypassed | runtime | Get: package management and package-inventory reads without the capability | `domains/packages.ts:145`, `:178` |
-| 56 | Activation write / authoring refusals do not fire | runtime | Get: activation artifacts writable and authorable without the activation-authoring capability | `activation-gate.ts:139`, `:190` |
+| 56 | Activation write / authoring refusals do not fire | runtime | Get: activation artifacts writable and authorable without the activation-authoring capability | `activation-gate.ts:138`, `:189` |
 | 57 | Automation run-state read, flow-authoring write and unrelated-screen read all pass | runtime | Get: run state, flow writes and screen reads with no grant | `domains/automation.ts:254`, `:545`, `:635` |
 | 58 | Audience-binding suggestion recording skipped | plugin-security | Lose: install-time suggestions are not recorded for system callers | `suggested-audience-bindings.ts:703` |
 | 59 | Email-template / webhook provenance stamps skipped | plugin-email, plugin-webhooks | Lose: the row is not marked as an admin customization | `email-template-provenance.ts:59`, `webhook-provenance.ts:50` |