feat: add minecraft-plugin-development skillFeat/minecraft plugin development (#1454)

* feat: add minecraft-plugin-development skill

* docs: expand minecraft plugin skill patterns

* docs: add minecraft skill examples

* docs: generalize minecraft skill patterns

* docs: expand minecraft progression guidance

* docs: add minecraft plugin validation workflow

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Co-authored-by: jiang <helloworld@jiang.cn>

skills/minecraft-plugin-development/references/state-sessions-and-phases.md

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+# State, Sessions, And Phases
+
+Use this reference when designing player state, match flow, cooldowns, respawn logic, class selection, or round progression.
+
+## Session modeling in real plugins
+
+### Rich minigame session
+
+Feature-heavy minigames often keep rich per-player runtime state in `PlayerSession`, including:
+
+- current team
+- kill and final kill counters
+- death flag
+- persistent potion-like buffs
+- selected brands grouped by category
+- per-brand cooldowns
+- special item cooldowns
+
+This is a strong pattern for feature-heavy minigames where one player can carry many temporary gameplay modifiers.
+
+### Lean persistent-brawl session
+
+Persistent brawl modes often keep a leaner `PlayerSession`, including:
+
+- `PlayerState`
+- selected hero
+- fall protection state
+- safe-zone tracking
+- generic cooldown map
+
+This is a strong pattern when the plugin has one dominant game loop and most feature-specific behavior lives in services.
+
+## Rule 1: model player state explicitly
+
+Do not infer state from inventory contents, world, or scoreboard text alone.
+
+Prefer an enum or similarly explicit model such as:
+
+- `LOBBY`
+- `RESPAWNING`
+- `IN_BRAWL`
+- queueing
+- spectating
+- eliminated
+- reconnect-pending
+
+## Rule 2: use sessions as the source of temporary truth
+
+Good session contents:
+
+- cooldowns
+- selected class or hero
+- selected team
+- in-round modifiers
+- safe-zone knowledge
+- reconnect markers
+- fall protection or spawn protection
+
+Avoid placing these as scattered listener fields.
+
+## Rule 3: gameplay phases deserve first-class objects
+
+Observed match-heavy minigame pattern:
+
+- `GamePhase`
+- scheduled phase transitions
+- boss and bed-destruction events tied to phases
+- phase-dependent spawners and world border changes
+
+Guidance:
+
+- for round-based modes, use a phase enum or state machine
+- trigger map-wide events from phase transitions, not random listeners
+- keep the “what happens at phase N” logic centralized
+
+## Rule 4: match overlays should not be mixed blindly into normal rounds
+
+Observed match overlay pattern:
+
+- `MatchManager`
+- `MatchSession`
+- separate handling for participants, observers, reconnects, brand rules, and round interception
+
+Guidance:
+
+- if tournament or match mode changes the base game rules, isolate it behind a dedicated manager
+- keep “normal game” and “match override” behavior composable, not tangled
+
+## Rule 5: reconnect and cleanup paths matter
+
+Observed concerns:
+
+- match participants may disconnect and reconnect
+- game sessions can outlive the current online `Player` object
+- cleanup must happen on quit, death, round end, and plugin shutdown
+
+Guidance:
+
+- prefer `UUID` for durable identity
+- if you must keep live `Player` references, also define detach/reattach behavior
+- always think through quit, reconnect, death, respawn, and shutdown together
+
+## Rule 6: cooldowns should be centralized
+
+Observed patterns:
+
+- Some match-heavy minigames tick cooldown maps during stage task updates
+- Some persistent-brawl modes store cooldown expiry timestamps in session data
+
+Choose based on your mode:
+
+- tick-down integers:
+  - good for per-second synchronized gameplay pacing
+- expiry timestamps:
+  - good for lightweight cooldown checks across arbitrary actions
+
+## Practical design heuristic
+
+If your feature changes what a player is allowed to do for some period of time, it probably belongs in session state.
+
+If your feature changes what the whole match is doing, it probably belongs in game or match state.