fix(cli): alias alert/channel single-record reads to the get/detail spellings

[ysyneu]

Problem

The verb for fetching a single record is spelled inconsistently across resources:

• incident answers both get <id> and detail <id>.
• alert answers only get <alert_id> — flashduty alert detail <id> fails with unknown command "detail".
• channel answers only the path-derived info <channel-id> — flashduty channel get <id> and flashduty channel detail <id> both fail.

These slips are mechanically unambiguous — there is exactly one single-record read per resource — but they cost the caller an error round-trip (the did-you-mean hints still require a retry).

Change

Aliases make the slip free; the canonical verbs are unchanged.

• alert get gains alias detail, matching incident's get/detail pair.
• channel info gains aliases get and detail. The channel command tree is generated by internal/cmd/cligen, so the aliases live in a new opAliases map in the generator — keyed by operationId, the same pattern as the existing positionalOverride — and are emitted into the generated command. They survive go run ./internal/cmd/cligen (verified: re-running the generator produces no drift).

Nothing else is aliased or renamed; help text is untouched beyond what cobra renders for aliases.

Behavior

• flashduty alert detail <id> → same request as alert get (POST /alert/info).
• flashduty channel get <id> / flashduty channel detail <id> → same request as channel info (POST /channel/info).
• Truly unknown verbs keep the existing loud failure, including did-you-mean suggestions for near misses (e.g. alert gt → suggests get).

Verification

• New tests in internal/cli/verb_aliases_test.go: alert detail and channel get/detail are asserted to hit the same wire path and body as their canonical verbs (against the httptest stub); --help through an alias renders the canonical command's help; alert show / channel show still fail with unknown command, and a near-miss typo still gets a suggestion block.
• make check (gofmt/gci, golangci-lint, go test -race ./..., build) — green.
• make check-cards (skill command-cards vs command tree) — green.
• Smoke: ./bin/flashduty alert detail --help prints the alert get help; ./bin/flashduty channel get --help and channel detail --help print the channel info help; ./bin/flashduty channel show 1001 errors unknown command "show" for "flashduty channel".

Note: go test -race -count=2 ./internal/cli/ trips a pre-existing test-harness gap (resetFlagSet doesn't reset int-slice flags, so TestCommandIncidentCreateSetsAssignType sees accumulated person_ids on the second in-process run). It reproduces identically on main without this change and does not affect the default count=1 runs used by make test and CI.