Fix up all review comments in SSH PR

[jescalada]

Issue for tracking finos#987 comment resolution status

[fabiovincenzi]

I've analyzed all unresolved review comments and verified their status against the current implementation.

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Resolved (File Removed or Code Refactored)

These comments are no longer applicable because the related code has been removed or completely rewritten:

Comment	Status
SSHKeyManager encryption key	File removed - SSH Key Retention replaced with Agent Forwarding
SSH TOFU check skipped	Implemented in sshHelpers.ts:78-91 with hostVerifier and knownHosts.ts
captureSSHKey buffer handling	File removed - no longer storing keys
captureSSHKey memory cleanup	File removed
SSHKeyForwardingService typing	File removed
SSHAgent key limit	File removed - using system SSH agent
SSH_KEY_RETENTION.md docs	Removed - feature replaced by agent forwarding
pullRemote complexity	Refactored into PullRemoteBase, PullRemoteHTTPS, PullRemoteSSH classes
fs.existsSync called twice	Fixed in refactored PullRemoteSSH.ts
server.ts casting issues	Refactored - client handling improved
test/.ssh/host_key in repo	Removed from repository
urls.js port replacement	File converted to urls.ts and refactored
server.js TODO comments	Converted to TypeScript, TODOs resolved
Path resolution with ~	No longer applicable - host key path is auto-managed, not user-configurable

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Resolved (Implemented)

Comment	Implementation
removeSSHKey not implemented	src/cli/ssh-key.ts:91-141
ENOENT crash for missing host_key	hostKeyManager.ts auto-generates key
SSH key format validation	calculateFingerprint() validates before saving
Action chain not triggered	server.ts:392-400 routes through security chain
Duplicate SSH key handling	DuplicateSSHKeyError in db/file/users.ts:196
Mongo duplicate handling	Check implemented in db/mongo/users.ts:67-76
Username hardcoded to git	Documented - standard for GitHub/GitLab SSH
Authentication failure tests	test/ssh/server.test.ts has comprehensive auth tests
Extract getCookies() helper	Implemented in src/cli/ssh-key.ts:32-38
Extract key reading/validation	readPublicKey() in src/cli/ssh-key.ts:45-50
maxPackSizeBytes in schema	Already in config.schema.json:298-301

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No Action Needed

Comment	Reason
API_BASE_URL from ServerConfig	CLI is standalone, env var GIT_PROXY_API_URL is correct approach
Duplicate logic CLI vs ssh-key.ts	No duplication - packages/git-proxy-cli/index.ts has no SSH logic
1GB default pack size implications	Configurable via limits.maxPackSizeBytes, 1GB is reasonable default