client: Fix some politeia issues.

[JoeGruffins]

• Fix XSS risk: remove html.WithUnsafe() from goldmark renderer
• Fix SignMessage to decode base64 signature from RPC wallet
• Fix iterateTable swallowing errors (return nil -> return err)
• Make politeia init non-fatal so wallet still runs without it
• Add nil guards for c.politeia in all core politeia methods
• Move table/index setup after version check to avoid DropAll issues
• Add nil Vote check before dereferencing in CastVotes
• Fix division by zero when EligibleTickets is 0
• Fix lastSync stored on error (move from defer to after success)
• Fix swallowed error in spv AddressAccount
• Fix copy-paste error in proposalTokenCtx (host -> token)
• Make ProposalsInProgress failure non-fatal in apiStakeStatus
• Add bounds check before proposals[0] access
• Fix IsEqual to compare all meaningful fields
• Fix CSS selector bugs: missing commas, incorrect nesting
• Fix typos: politiaSyncing, nTicketAddresess, --text-sucess
• Fix async/await on loadPage calls in TypeScript
• Fix null safety for proposalsInProgress in wallets.ts
• Fix duplicate &status= in proposals pagination link
• Fix loadProposal query string format in wallets.ts
• Remove dead voteBitVerify function and unused imports
• Remove pre-selected active class on Yes vote button
• Rename versionTxt -> idVersionTxt for naming consistency
• Scope .card CSS override to proposal pages only
• Remove stale storm tags and dcrdata references