infra: move 'Calling canisters that require cycles' from cycles-management to inter-canister-calls

[marc0olo]

Problem

The section ## Calling canisters that require cycles in guides/canister-management/cycles-management.mdx is misplaced. It covers a call mechanic (attaching cycles to an inter-canister call), not an operational management concern. The cycles-management guide otherwise covers acquiring cycles, checking balances, topping up, freeze thresholds, and monitoring — all operational topics.

Proposed fix

Move the content into guides/canister-calls/inter-canister-calls.mdx as a new ## Calls with attached cycles section, covering:

• Attaching cycles when calling out (Motoko (with cycles = amount) syntax, Rust .with_cycles())
• Accepting cycles when receiving a call
• Proxy canister pattern for attaching cycles from the CLI

Affected files

• docs/guides/canister-management/cycles-management.mdx — remove the section
• docs/guides/canister-calls/inter-canister-calls.mdx — add the section
• docs/concepts/cycles.md — update link at line ~97 (currently cycles-management.md#calling-canisters-that-require-cycles)
• docs/guides/chain-fusion/exchange-rates.mdx — update link in "Testing from the CLI" section

Notes

• Do not start this until PR docs: migrate Learn Hub 'How does ICP work?' content into developer docs #208 (infra/learn-hub-migration-prep) is merged, as that PR touches several of the affected files.
• The proxy canister template lives at icp-cli-templates/proxy and is already documented in cycles-management; make sure the reference survives the move.