docs: correct config keys and stack output paths across component docs

[awdemos]

Summary

Corrects component docs that instructed wrong, dead, or stale configuration keys and stack-output paths (each verified against the code):

• invokeai.md — invokeai:enable → invokeai:enabled (the code reads enabled via config.isEnabled; following the doc deployed nothing)
• bitcoin-knots.md — bitcoin-core:maxconnections → bitcoin-knots:maxconnections
• mempool.md — dead key mempool:hostname → the real required keys mempool:frontend/hostname and mempool:backend/hostname
• kubeai.md — bogus pulumi set kubeai:enableMonitoring true → the real gate: prometheus:enabled + prometheus:enableComponentMonitoring
• nextcloud.md — duplicate nextcloud:storageSize (second line overwrote the first) → nextcloud:db/storageSize; "PostgreSQL" → MariaDB; documented the required nextcloud:trustedProxies and nextcloud:groupProvisioningWhitelist keys; fixed the OAuth snippet using $DISCOVERY_URL before it was defined
• transmission.md, seerr.md, prowlarr.md, ollama.md — stale .media.* / .ai.* jq prefixes on pulumi stack output (stacks export top-level clusterUrls / endpoints)
• ollama.md — removed HIP_VISIBLE_DEVICES / CUDA_VISIBLE_DEVICES (never read by the code); documented the AMD keys that are actually read (HSA_OVERRIDE_GFX_VERSION, HCC_AMDGPU_TARGETS)

Verification

Markdown-only — no tests needed per project convention. Every key/path cross-checked against the component source before editing.

[AdamNowotny]

Docs verified — all config-key and output-path corrections check out against the source and are correct:

• invokeai:enabled, bitcoin-knots:maxconnections
• mempool:frontend/hostname / backend/hostname (old mempool:hostname was dead)
• prometheus:enabled + prometheus:enableComponentMonitoring for kubeai
• nextcloud: db/storageSize, MariaDB, required trustedProxies / groupProvisioningWhitelist
• media/ai top-level .endpoints / .clusterUrls (no .media. / .ai. prefix)
• ollama: dropped *_VISIBLE_DEVICES, added HSA_OVERRIDE_GFX_VERSION / HCC_AMDGPU_TARGETS

One blocker: the branch conflicts with main in stacks/apps/components/nextcloud/nextcloud.md. main already replaced the manual OAuth snippet with ./components/nextcloud/pocket-nextcloud.sh, so the DISCOVERY_URL hunk is obsolete. Rebase and drop that hunk before merging.