import: filter & blocking batch (8 plugins)

[Aybook]

Third import batch. Eight filter / block / share-protection plugins, per-plugin layout per #2.

Plugins in this PR

Plugin	Upstream	Function	Notes
`etc_clientblocker`	v0.1 (english)	Block clients by AP regex pattern (DC++ 0.7xx, AirDC++ 2.xx, etc.)	Overlaps with luadch-ng issue #81 but offers value standalone
`etc_client_su_check`	v0.2 (english)	Warn / block users with invalid or missing SU (Supports Upgrade) feature flags	—
`etc_ccpmblocker`	v2.0	Control CCPM (client-to-client PM); flag removed by default, restored when both peers >= op_level	Normalised: scriptname `etc_ccpmblocker2.0` -> `etc_ccpmblocker`; filename also no longer carries the literal "2.0"
`etc_noadvertise`	v0.7 (multi)	Keyword filter for forbidden / advertised strings in main + PM	Database-driven, lang en/de, three state files
`etc_sslonly`	v0.2 (german)	Kick users on plain ADC, warn team	Filename `etc_sslonly_0.2.lua` normalised to `etc_sslonly.lua`. Complementary to luadch-ng issue #77
`etc_hide_announcer`	v0.01 (english)	Suppress user-announce broadcasts	Tiny
`ptx_anti_dl`	v2.0 (english)	Profile-based anti-download protection (search / download blocks)	Two state files at `scripts/data/` shipped as empty `return {}` placeholders so the data dir exists at first save
`ptx_tagcheck`	v2.3 (multi3)	Release-tag validation	Lang en/de/sv

Audit

• Lua 5.4 patterns: zero hits across all 8.
• BOMs at file head: stripped where upstream shipped them.
• No direct `cfg/user.tbl` access in any of the 8, so no v3.1.x adapt needed (unlike etc_NewPasswords in import: mod-tools batch (4 plugins, etc_NewPasswords v3.1.x adapt) #3).

Normalisations

Two filename / scriptname normalisations to keep things sane on disk and in lang lookups:

• `etc_ccpmblocker2.0` -> `etc_ccpmblocker`: dropped "2.0" from both the scriptname identifier and the file path. Lang loader (`cfg.loadlanguage(scriptlang, scriptname)`) would otherwise look up `etc_ccpmblocker2.0.lang.` which is awkward.
• `etc_sslonly_0.2.lua` -> `etc_sslonly.lua`: filename was version-stamped upstream while `scriptname` was already `etc_sslonly`; aligned them.

Both documented in the corresponding file's provenance header.

Test plan

• Drop all merged batches (import: chat & messaging batch (6 scripts) #1 chat&messaging, import: mod-tools batch (4 plugins, etc_NewPasswords v3.1.x adapt) #3 mod-tools, plus this one) into a fresh hub install, run the `luadch-ng/luadch` v3.1.1 smoke harness: 10 / 10 PASS including "no script errors in log".
• Functional tests per plugin (e.g. clientblocker against a fake AP, sslonly against a plain-ADC client) - deferred; load-clean is the floor.