fix(security): sentence case titles, rename decentralization to canister-control (#237)

## Summary
- Apply sentence case to all security guide page titles (matches portal
convention and brand rules)
- Add `sidebar.label: "Overview"` to overview page so navbar shows
"Overview" while page title remains "Security overview"
- Rename `decentralization.md` → `canister-control.md` (more accurate:
covers SNS governance, canister trust verification, and untrusted asset
loading)
- Remove "Security" from individual page titles within the security
section (the section heading already provides context, consistent with
original portal structure)
- Improve three descriptions: "endpoint verification" (was
"validation"), "timer reinstatement after upgrades" (was
"reinstatement"), added "mobile Internet Identity integration" to IAM
description

## Sync recommendation
hand-written (title/description metadata changes only; content
unchanged)

Author: marc0olo

docs/guides/security/decentralization.md docs/guides/security/canister-control.mddocs/guides/security/decentralization.md renamed to docs/guides/security/canister-control.md

@@ -1,6 +1,6 @@
 ---
-title: "Decentralization"
-description: "Security best practices for distributed canister control using the SNS, governance mechanisms, and reducing centralized trust."
+title: "Canister control"
+description: "Security best practices for canister control: using governance frameworks such as the SNS, verifying the trust level of canisters you depend on, and loading assets only from trusted domains."
 sidebar:
   order: 10
 ---

docs/guides/security/canister-upgrades.md

@@ -1,6 +1,6 @@
 ---
-title: "Canister Upgrade Security"
-description: "Security best practices for canister upgrade hooks, panics during upgrades, and timer reinstatement."
+title: "Canister upgrades"
+description: "Security best practices for canister upgrade hooks, panics during upgrades, and timer reinstatement after upgrades."
 sidebar:
   order: 8
 ---

docs/guides/security/data-integrity-and-authenticity.md

@@ -1,5 +1,5 @@
 ---
-title: "Data Integrity and Authenticity"
+title: "Data integrity and authenticity"
 description: "Security best practices for certified variables, asset certification, and protecting data authenticity on ICP."
 sidebar:
   order: 4

docs/guides/security/data-storage.md

@@ -1,5 +1,5 @@
 ---
-title: "Data Storage"
+title: "Data storage"
 description: "Security best practices for canister data storage, stable memory, encryption of sensitive data, and backups."
 sidebar:
   order: 3

docs/guides/security/dos-prevention.md

@@ -1,5 +1,5 @@
 ---
-title: "Denial of Service Prevention"
+title: "DoS prevention"
 description: "Security best practices for protecting canisters against DoS and DDoS attacks, noisy neighbors, and expensive calls."
 sidebar:
   order: 7

docs/guides/security/formal-verification.md

@@ -1,5 +1,5 @@
 ---
-title: "Formal Verification"
+title: "Formal verification"
 description: "Applying formal verification and TLA+ model checking to find and prove the absence of security bugs in ICP canisters."
 sidebar:
   order: 12

docs/guides/security/https-outcalls.md

@@ -1,5 +1,5 @@
 ---
-title: "HTTPS Outcall Security"
+title: "HTTPS outcalls"
 description: "Security best practices for canister HTTPS outcalls: API keys, rate limits, idempotency, response consistency, and input validation."
 sidebar:
   order: 6

docs/guides/security/identity-and-access-management.mdx

@@ -1,6 +1,6 @@
 ---
-title: "Identity and Access Management"
-description: "Security best practices for authentication, anonymous principal rejection, ingress message inspection, and session management."
+title: "Identity and access management"
+description: "Security best practices for authentication, anonymous principal rejection, ingress message inspection, session management, and mobile Internet Identity integration."
 sidebar:
   order: 2
 ---

docs/guides/security/inter-canister-calls.md

@@ -1,5 +1,5 @@
 ---
-title: "Inter-Canister Call Security"
+title: "Inter-canister calls"
 description: "Security best practices for handling traps in callbacks, message ordering, rejected calls, and untrustworthy canisters."
 sidebar:
   order: 5

docs/guides/security/miscellaneous.md

@@ -1,6 +1,6 @@
 ---
-title: "Miscellaneous Security Practices"
-description: "Miscellaneous security best practices: data confidentiality, secure randomness, endpoint validation, testing, reproducible builds, monotonic time, and floating point."
+title: "Miscellaneous practices"
+description: "Miscellaneous security best practices: data confidentiality, secure randomness, endpoint verification, testing, reproducible builds, monotonic time, and floating point."
 sidebar:
   order: 11
 ---