refactor: centralize constants and eliminate magic strings

[shivv23]

Centralizes all magic strings, hardcoded values, and repeated literals into a single src/constants.ts module, eliminating ~110+ scattered occurrences across 10 files.

Motivation

The codebase contained dozens of repeated hardcoded strings — IPFS gateway URLs, activity type literals, metric keys, storage key names, connection status strings, route paths, email configuration, and magic numbers. These were scattered across components with no single source of truth, making renaming, configuration changes, and internationalization fragile and error-prone.

Changes

New file: src/constants.ts — single source of truth for all application constants:

Category	Constants	Occurrences Eliminated
Infrastructure	IPFS_GATEWAY_URL, PROVIDER_NAME	9
Storage Keys	STORAGE_KEY_BACKUP_HISTORY, STORAGE_KEY_ACTIVITY_LOGS, STORAGE_KEY_METRICS	7
Activity Types	ActivityType (typed const enum)	11
Metric Keys	MetricKey (typed const enum) + DEFAULT_METRICS	17+
File Sentinels	DEFAULT_FILE_NAME, RESTORED_INVOICE_DEFAULT	12
Routes	ROUTES.HOME, ROUTES.MESHKIT, ROUTES.ROOT	6
Connection Status	ConnectionStatus (typed const enum)	12
View Modes	ViewMode (typed const enum)	8
Toast Config	TOAST_DURATION_LONG, TOAST_DURATION_SHORT, TOAST_POSITION	6
Magic Numbers	MAX_ACTIVITY_LOGS, MAX_FILENAME_LENGTH, CID_DISPLAY_LENGTH, MAX_ACTIVITY_DISPLAY	5
Email	EMAIL_RECIPIENT, EMAIL_BODY_DEFAULT, EMAIL_ATTACHMENT_NAME	3
Report	REPORT_FILENAME, REPORT_HEADER	2

Refactored files:

• LocalStorage.ts — storage keys, activity type union, metric defaults, activity limit all use constants
• MeshkitService.ts — provider name uses PROVIDER_NAME
• Dashboard.tsx — gateway URL, activity types, metric keys, file sentinels, connection status, report config, toast config, route paths, CID display length, activity display limit
• Menu.tsx — email configuration, file sentinels, filename length limit, toast duration/position
• NewFile.tsx — default file name sentinel
• Home.tsx — view mode enum, default file name
• MeshKit.tsx — connection status, metric keys, gateway URL, CID display length, toast config, route paths
• BackupSuccessModal.tsx — gateway URL
• App.tsx — route paths

Type safety:

All string union types (ActivityType, MetricKey, ConnectionStatus, ViewMode) are defined as as const objects with companion type exports, providing both runtime values and compile-time type checking.

Type infrastructure:

• Added src/types/meshkit-ionic.d.ts type declaration stub for @meshkit/ionic

Before / After

// Before: hardcoded in 5 files
"https://gateway.pinata.cloud/ipfs/${cid}"
await store._incrementMetric('invoicesBackedUp')
await store._logActivity({ type: 'BACKUP', ... })
if (connStatus === 'Online') { ... }
history.push("/meshkit")

// After: single import from constants
import { IPFS_GATEWAY_URL, MetricKey, ActivityType, ConnectionStatus, ROUTES } from "../constants";
`${IPFS_GATEWAY_URL}${cid}`
await store._incrementMetric(MetricKey.INVOICES_BACKED_UP)
await store._logActivity({ type: ActivityType.BACKUP, ... })
if (connStatus === ConnectionStatus.ONLINE) { ... }
history.push(ROUTES.MESHKIT)

Verification

npx tsc --noEmit passes with zero errors.