Rename `FastMCP` to `MCPServer` #364

Job	Run time
checks / readme-snippets	10s
checks / pre-commit	31s
checks / test (3.10, lowest-direct, ubuntu-latest)	54s
checks / test (3.11, locked, ubuntu-latest)	45s
checks / test (3.13, lowest-direct, windows-latest)	2m 43s
checks / test (3.12, lowest-direct, ubuntu-latest)	55s
checks / test (3.12, locked, ubuntu-latest)	53s
checks / test (3.14, locked, ubuntu-latest)	2m 18s
checks / test (3.13, lowest-direct, ubuntu-latest)	53s
checks / test (3.10, lowest-direct, windows-latest)	2m 34s
checks / test (3.11, locked, windows-latest)	3m 10s
checks / test (3.12, locked, windows-latest)	3m 27s
checks / test (3.11, lowest-direct, ubuntu-latest)	51s
checks / test (3.10, locked, windows-latest)	2m 17s
checks / test (3.11, lowest-direct, windows-latest)	2m 40s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 22s
checks / test (3.14, lowest-direct, windows-latest)	2m 48s
checks / test (3.12, lowest-direct, windows-latest)	3m 34s
checks / test (3.10, locked, ubuntu-latest)	52s
checks / test (3.14, locked, windows-latest)	3m 32s
checks / test (3.13, locked, windows-latest)	2m 32s
checks / test (3.13, locked, ubuntu-latest)	43s
all-green	3s
	40m 27s

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